Gillian dropped the leaf in her hand as if she'd been burnt by fire and looked up around the room. She reprimanded herself for her childish reaction; of course no one was watching her. No one had seen it because no one was there. She was alone, in her house. And even if, it was Cal's decision not hers. She felt so flattered. She'd never had a book dedicated to her. Cal had dedicated his first book to his mother posthumously. Gillian never expected to find her name next to Emily's, never mind the touching words that accompanied the dedication. She amazed him. She snickered. Served him right, for all the times he'd confused her with his strange behaviour!

She leaned forward and lifted the bound manuscript out of the shoebox. She thumbed it quickly through. Wow. 387 pages. Considering Cal had had no idea what to write he had a lot to say in the end. She flipped over the title page and the dedication and saw Emily's foreword. She quickly scanned it through and smiled, reading about Emily's experience of living with a human lie detector for a father. The teenager really had a way with words, definitely not a character trait she'd inherited from her father, who almost always seemed to struggle expressing himself verbally.

She laughed out loud when Emily admitted at the end that she did cause the fire in their backyard eight years ago and asked Cal not to ground her when he read this. There was a note from Cal to Emily after her foreword: "Don't worry, you're not grounded. But just for that lie I wrote a whole chapter on you and included an embarrassing picture."

It had always warmed her heart to see Cal interact with his daughter. They were so cute together. He could be in the grouchiest mood from interviewing a criminal scumbag but the minute Emily walked into a room his eyes lit up and his spirits lifted. Cal was a great father and Emily kept him grounded… and from taking too high risks. They actually had a very mature relationship, Cal never talked down to her because she was a child. Even when Emily was a six-year-old, Cal treated her like a little adult with her own personality. She'd giggled the first time she'd seen an exchange between Cal and Emily, which revolved around the correct use of the word ubiquitous. She'd never met a six-year-old before who knew what ubiquitous meant, let alone argue about its correct use in a sentence. No wonder Emily would go on to sweep the board of local spelling bee competitions. Cal had garnered her awards in his study like prized possession; one might be misled he'd won them.

Gillian perused the table of contents and realised that this book took on a much more personal nature than the first one and had completely changed from the first draft he'd shown her. From what she gleaned from the chapter titles, Cal had mixed professional cases with personal stories. Zoë and Emily each had their own chapter; she presumed that Radical Honesty and Naturals dealt with Loker and Ria respectively. The Long Con was undoubtedly about the Jenkins case. Cheating Spouses was a no brainer. Devils in Disguise was probably about Martin. Gillian began to flip back and forth between the table of contents and the chapters to confirm her suspicions. She wondered whether A Fine Line was her – the only name she couldn't find among the list of names or telling descriptors in the table of contents was hers. That stung a little. Even Terry had made it there. His parents. And some Bonnie. Who on earth was Bonnie? He'd never mentioned her before. She also must be someone from his past. Maybe a mutual friend of his and Terry's? Gillian hated to admit it, but after last night especially, it hurt just a little bit that she didn't make it into his book. Even Loker had! She told herself that Cal was writing his book while they weren't exactly on speaking terms at work, so he probably didn't want to drag his work problems into his new book. Writer's block was the last thing he needed. Never mind the part where Zoë would blow a fuse if she found out Gillian made her way into his book.

Gillian put the manuscript on her coffee table and went into the kitchen to get a glass of wine. There was just enough left over from last night. Then she settled onto her couch, nestled into her favourite throw, and began to read Cal's introduction.

I had a hard time writing this book. In fact, I had such a hard time writing this book that I briefly considered signing up for Facebook when, luckily for me, I stumbled across an online poker website. Truth be told, I didn't know what to write. I gave you the science in my first book, what more do you want? What more could you need? You have the science now use it or leave it be. Right?

Wrong. Maybe writing my first book was a mistake. Maybe I opened a can of worms I cannot close again. At the time it seemed like a good idea to share with the world what I know but now I am not so certain anymore. Let me tell you why in this book.

If there is one thing I've learned in my life, it is that you can have truth or happiness but never both. Knowing what someone else is feeling, being able to remotely guess what someone might be thinking, is less of a blessing than a curse in real life. Don't get me wrong, it's really great in my line of work to pick out the liars and the cheaters and take home a mighty pay check for an hour's worth of looking someone in the face – especially if it happens to be the one of a pretty trophy wife.

You see the problem is you may know that someone is lying, but you don't really know why. You can't read that on a face. You need to dig deeper for that. You need to communicate to get to the bottom of the problem. I learned that the hard way. It cost me a marriage that had no chance of surviving under the scrutiny I put my wife through every day, calling her out on the slightest signs of deception I could detect. A friend taught me that the why is just as important as the how people are lying; unfortunately by the time she imparted that wisdom onto me, it was already too late for my marriage. I thought I was the perfect husband, building my marriage on a foundation of truth, but as my ex-wife once told me, there really is such a thing as too much honesty in a marriage.

Having relationships is not easy when you have my talents. I cannot turn it off. I can see everything. I know when my daughter doesn't want to go to summer camp anymore, even though she's trying to convince me of the opposite. I see when my date is more interested in the cute but possibly underage waiter who serves our table. My friends can't throw me a surprise party for my birthday because I read it on their face the minute they hatch the plan. Which, let me tell you, is all in all a good thing because birthday parties suck in the first place.

I don't know, though, why my daughter doesn't want to go to summer camp anymore. She probably doesn't know yet herself. But I can see it and I have to make the decision whether to call her out on her lie or leave it be and let her figure it out on her own. I don't know why a woman finds the waiter more interesting than me. Is he more attractive? Am I too old? Do I bore her? Hell, if I know.

Let me be clear. I understand very little, least of all the people around me. So if I, who developed and perfected this science, don't really understand the people around me, how could I unleash such a beast on you the readers? The least I can do is show you when my science works and when it doesn't, so you won't make the same mistakes. Let me give you a hint, my science works great at my job and I have compiled a few of the more interesting cases my company has consulted on in the last five years. But if you think you know the science after reading my first book and are ready to confront your husband about his philandering ways…he may just be hanging out at the golf club with his mates or trying to surprise you for your birthday.

A warm tingle spread through Gillian's body as she read Cal's introduction. She had no trouble recognising herself in "his friend" and in a way it was ironic that both of them had helped salvage each other's respective marriages, even if it was too little and came too late.

She continued reading, and the first chapter A Fine Line dealt with Cal coming to terms with running his own company without alienating his staff. He focused on working relationships, managing subordinates and the guiding principles they'd come up for the company's mission and their workplace environment. She chuckled when Cal recounted how during the first month their research staff showed up late in the mornings, rotating through a roster of lame but creative excuses to test their new boss's patience. Cal turned it into a game to train them in facial recognition and picked a liar of the day and asked the rest of the staff to find out which one among them was the liar and what the three lies were they'd told them over the course of the morning. Gillian had made it a fixture of their early company retreats to build a good workplace environment. It also described how their professional relationship grew from mutual respect into a wonderful friendship. Gillian chuckled, when Cal accredited her people skills for the fact that the staff hadn't quit yet or staged a mutiny – thank God for company retreats. Gillian enjoyed the walk down memory lane as Cal recounted the founding years of their company and inevitably delved into their famous "line", pondering how far it was appropriate to meddle into someone else's life when they weren't just a business partner but had also become your best friend.

Cal began the second chapter with a mini rant about the plights of fatherhood, especially raising a beautiful and smart teenage daughter. He confessed he thought about hiring a contractor to build a dungeon in his house when boys started to notice his Emily but then his divorce happened and it would have been a mute point anyway because of a shared custody agreement. As he wrote on, Cal grew more serious, detailing how fantastic he thought his science was when Emily was a baby and toddler and he could know with just a look at her face what she needed. It was a surprise Emily learned to talk at all, given that her father had catalogued her cries and facial expressions after five months, laying out when she was hungry, hurting, tired or just looking for attention and closeness. Cal admitted that writing about it made him realise how frustrating this connection must have been for his young wife. Just a glance at her chubby toddler face and he knew Emily needed a hug because something had made her sad. A little flick of her eyes and he knew she hadn't washed her hands before dinner. Nothing went by him. He felt like Superdad and the way Emily looked up to him really made him believe he wore a cape and had a big capital S emblazoned on his chest. He was her hero and he admitted it was the best feeling he'd ever experienced. Better than catching #2 on the FBI's most wanted list, better than being the world's leading expert in deception detection, better than sex.

Gillian was touched as she read about Cal's struggles as a young father who was juggling toddler tantrums and terrorists. His work often kept him away from his family for periods of time and made him realise that he was bringing up a child in a world that got increasingly more dangerous and unsafe with every day she lived. Despite his best efforts in counter-terrorism, there was nothing he could really do to ensure Emily's safety, short of shrouding her in ten layers of bubble wrap. So how did you raise a child when you spent more time with the darkest elements of humanity than with your family? It doesn't get easier as they grow, Cal explained. Far from it. The cute little girl with ponytails turns into a moping teenager, a cell phone replaces the umbilical cord, and super dad becomes the ogre who won't let her date and go out to parties. And you wish you could explain to them, why you are so protective, because the world is a scary and unsafe place but you don't want them to grow up paranoid, either. So what do you do?

In the end, Cal reasoned, he realised that nothing of all that would matter if he didn't raise his daughter to become a self-confident, compassionate and smart young woman. And Emily had really done him proud. He admitted that all fathers claimed that their baby was the most beautiful one in the maternity ward, the smartest kid in school and the prettiest girl to have ever graced the earth. Only in his case, it was true.

Gillian laughed out loud, when she flipped the page and saw which picture Cal had included to illustrate his point. It looked similar to the one he had of Emily in his office, the one where she was wearing the over–sized sun glasses but on this one she was sticking out her tongue and pulling the corners of her mouth apart with her index fingers. A real keeper that one, isn't she , the caption read and Gillian remembered Cal threatening to get back at Emily for the lie she confessed in her foreword.

Cal finished the chapter with a brief list of typical teenager lies he'd encountered with his own daughter. He explained for parents how to spot when their children were lying about their homework, sneaking out for parties or meeting friends. Cal described how he tried to handle the situations, when to trust his daughter's judgement and when to call her on her deception. He made it clear, though, that he would never let it slide if Emily lied about drugs or alcohol. He drew the line at his concern for her safety and well-being. Using a white lie because she got an F on an arts project was one thing, lying about flunking the SAT required a sit down and talk. Not that his darling brilliant daughter could ever flunk the SAT. Cal confessed that he actually enjoyed the little games Emily played with him, seeing if she could sneak a lie past him. And he admitted that sometimes she succeeded. Like with the fire.

He conceded that children and teenagers were entitled to their own secrets in the process of forming their own identities. A concept that was so foreign to him originally, that he had a hard time coming to terms with the idea his little girl might want to hide something from him. It took him a while to understand that if he didn't accept that as part of Emily growing up, he would lose her forever. He had to pick and choose his battles and trust that Emily would come to him for advice when she needed it. He could only hope that giving her the space she needed would ultimately encourage her to share more of her life with him than hide it.

Gillian thought back to last summer when Cal had freaked out about Emily losing her virginity. He probably still hadn't recovered from the shock that she'd managed to hide that from him for as long as she did. And again, she had no problem identifying herself as the friend who imparted her wisdom – though Cal had called it psychobabble at the time – onto him. In a way that felt almost more flattering than if she'd gotten her own chapter. It showed how inextricably linked her and Cal's lives were even before they'd started dating. They'd always been an item, professionally, intellectually and now even romantically. They were two sides of a coin.

She skimmed the next chapter, which dealt with one of their very first cases, the church bomber, which they often used as a case study in their seminar talks. Gillian laughed out loud when she read Cal's last footnote on the Cheating Spouses chapter: "If you're now thinking about hiring me for your divorce, please call the following hotline: 212-555-2342." Gillian looked up and reached for a pencil that conveniently lay on her coffee table. She quickly made a note to call Cal's publisher and tell them to edit that footnote out… For she'd immediately recognised the number as belonging to Radar's firm. Nice try, Cal, passing off those cases to Radar.

Gillian soaked up Cal's writing, browsing through the case chapters and indulging in the ones where he explored his interpersonal relationships; and before she knew it she'd arrived at the final chapter. She wiggled her eyebrows in anticipation of finally learning more about this Bonnie but she stopped dead after reading the first sentence.

It has been said that every Bonnie needs her Clyde – so naturally this Clyde would be nothing without his Bonnie.

Gillian gasped. He wouldn't. He didn't. Her heart suddenly started beating faster and her hands grew a little sweaty. She'd really not expected her own chapter after the numerous references to her throughout the book. And the fact that he referenced their conversation in the car, made the whole thing even more endearing to her. She continued reading.

I met my partner in crime many years ago at the Pentagon. For matters of national security I am not at liberty to tell you how exactly our paths crossed, but Bonnie quickly impressed me with her perceptive skills and her ability to read people. In fact, she told me right off the bat in one of our first meetings, where the fault in my work lied, namely, that I am predominantly interested in deception detection without digging deeper for motivation. I knew she was a keeper right then and there. I should have known I was in trouble right then and there.

Most people grow very uncomfortable around me, when they learn what I do for a living, and even in professional circles, people clam up and eye me suspiciously while keeping their distance. I definitely think it's no coincidence that I always have breakfast alone at conferences. Bonnie, however, had no reservations at all, on the contrary she went toe to toe with me right from the start. I loved it. Finally someone who understood me and challenged my work. Bonnie saw beyond the immediate application of my work in counter terrorism for which it was developed and lectured me on how much greater good my work could do if I rendered my services to other agencies, even in the private sector. It was just a question of time until I recruited Bonnie to work with me, when I left the Defense Department. She will insist that I practically fell down on my knees and promised her the moon and the sky if she started a private consulting firm with me, and of course she'd be telling you the absolute truth.

For the truth is, I could not do my work without Bonnie. She's the one who keeps the company ship afloat and the disgruntled employees from strangling me during lunch break. True story, I was once attacked by a suspect during an interrogation. I'd misjudged his level of distress and antagonised him too much. Before I knew what had happened he had me in a headlock and was squeezing the living daylights out of me. Bonnie managed to talk him down with her über-diplomacy and thanks to my then wife's Harvard law degree we even cashed in a nice check from the FBI for fear we'd sue them over the malfunctioning shackles that made the attack on me even possible. We used that money to rent our first office space downtown D.C. and hire our first employee, Jack Radar, whom you met in the very first chapter.

Bonnie may not be a natural and I taught her everything I know but her understanding of the human condition and psyche have enhanced my work over the past ten years in ways I could have never imagined. People lie all the time, but the critical information lies in the reasons why they lie. It's the same with lie detectors, they only tell you that someone is anxious or stressed but they don't tell you what the subject is excited or nervous about. A lot of our early cases dealt with people who protested their innocence after a failed polygraph test. Looking back, I think that oftentimes the situations we dealt with at the FBI and DoD lent themselves to a "shoot first, ask questions later" policy. Sometimes that lead to dreadful mistakes but to some extent I could understand it. It's more important to find out what a terrorist is lying about and where his target is than his motives for trying to bomb us to thy kingdom come. You can save those questions for after you've saved the world. But the things I've seen…let me just say that I have always been on the fence regarding this issue. It's better to let one guilty man off the hook than torture an innocent civilian.

I wonder whether Clyde ever worried about his Bonnie the way I do about mine. Some days I am not entirely convinced that I did the right thing in letting Bonnie become my partner in crime. It's not because I'm a chauvinist who thinks his line of work is too dangerous for women. Working with criminals and terror suspects certainly carries a higher risk than selling books but all the women I have ever collaborated with have been able to hold their own in this admittedly male dominated world. Ria Torres and Gillian Foster are certainly no exception to that rule; on the contrary, they both lead by shining examples how it's done. And yet, sometimes when a case hits too close to home, I am reminded I could never forgive myself if something happened to my Bonnie.

I have this uncanny talent to turn a potentially harmless situation into a moderately sized nuclear accident… which would be fine if it weren't for Bonnie getting caught in the midst of it. I know Bonnie thinks at times I am overprotective and patronising when I won't let her tag along on one of my crime sprees, as she calls them, but honestly, it's out of pure self-preservation. I can't concentrate on doing my job if I have to worry about Bonnie's well-being and I wouldn't know what to do if I lost her. After all, 8 out of 10 times Bonnie has to come to my rescue and save my arse because I didn't heed her advice earlier on in the first place. So a lot of times it's really like being caught between a rock and a hard place. Damned if I bring her along, doomed if I forge ahead without her.

I can't help but want to protect Bonnie from the evils of this universe. The world has not been kind to her but you wouldn't hear Bonnie complain about any of the hardships she went through. She's tough as nails that one. She's faced serial killers and terrorists, once single-handedly disarmed a knife-wielding psychopath, and most importantly, she's crazy enough to put up with me day after day. You do not want to cross Bonnie. And yet she's got so much love in her heart, the world is not big enough to soak it up. She's an inveterate optimist. She makes me want to believe that truth and happiness are not irreconcilable. She gives me hope that you can have both in your life. Women like Bonnie are of a rare kind, the kind of pure and perfect breed of a unicorn. You don't really know they actually exist until you meet one of them. You hope it but you know better. And then once you met them, you have no idea how you could ever live again without them in your life.

The truth is I could not live without Bonnie. I need her because she makes sure I remain an upright citizen and productive member of society. I have a special talent for alienating people with my line of work, my daughter thinks I am a bully, but really I am just trying to alienate my targets enough to get them out of their comfort zone. Bonnie makes sure I don't get killed in the process. (Though sometimes I get the distinct impression she would like to off me… like the one time she kept ogling a lead pipe to club me over with at a construction site where I'd antagonised one of the witnesses too much.) It scares me how indispensable Bonnie has made herself in my life. I don't think she planned it or did it on purpose. It just happened. She's my partner in crime. I'm her work in progress.

What scares me the most is that besides Emily, Bonnie is the only person who can lie to me. Emily grew up with me and learned from the best, but Bonnie doesn't even like lying. And it's not like the game Emily and I play, trying to sneak little lies past each other. For the longest time I thought Bonnie was the most terrible liar in the world until I found out that the old saying really is true. Still waters run deep. Try as I might, I can't read her the way I want to.

I have a theory about so-called blind spots, i.e. people in our lives we are so close to we can't interpret micro-expressions correctly. We find the idea that our spouses, our best friends could betray us unfathomable, which makes the betrayal in the end all the more hurtful. While I can read my ex-wife like an open book, I simply couldn't fathom the idea that my wife could ever leave me so I ignored all the signs. I didn't want to see them, so when I came home one day to her suitcase in the hallway, she might as well have punched me in the gut. A husband who can't fathom his wife could ever cheat on him, blocks out all the signs pointing him in the right direction, which is why the cuckold usually finds out last. I've dealt with clients, both female and male, who flat out refused to believe their spouse cheated on them, making excuses for them even after I confronted them with incriminating footage.

I might as well have called this chapter Blind Spots because Bonnie is definitely my blind spot. She may be the world's most terrible liar most of the time but when lives are at stake she'll sell you a private beachfront property in Arizona and make you send a postcard. I think it's because Bonnie believes that the truth will set you free. She sees no use in lying. Unlike Emily who considers it a game, Bonnie just doesn't like to lie. Naturally, it drives me crazy when she keeps something from me. It's not so much that she wants to hide something from me as that I can't figure it out. Yes, I do like to meddle in her business, but it's more than that. I'm not used to having to prod for information, most people are like open books for me. And in the beginning Bonnie was so easy to read for me too but somewhere along the line (no pun intended!) I lost my touch – which only speaks for my blind spot theory.

Ultimately I think it puts a strain on my relationship with Bonnie because unlike most people I am aware that she is my blind spot. I meddle with her life when I know she is trying to keep something from me, and I meddle with her life when she isn't because I am worried she might keep something from me without my knowledge. There, I admit it. She makes me insecure. Like I've lost my magic touch. And while I find this to be very frustrating and confusing, the other side of the coin is that this is exactly what makes Bonnie so intriguing for me. It's like a challenge. I can't always read her. She's not like an open book for me and yet I want to browse through the pages of her life story more than any other person I've ever met. I've never wanted to truly understand another person as much as I want with Bonnie. She is the most fascinating person I have ever met, and the complexities of her personality are like an enigma I just have to solve. Some days I'm afraid she's literally driving me crazy.

The chirp of her cell phone tore Gillian out of her thoughts and she quickly went in search of the item. Where'd she left it last night? She followed the sound and groaned frustrated when it stopped. She looked at her watch and realised it was 7pm. How long had she been reading on her couch? Her heart started to beat faster as she realised it was probably Cal checking in on her telling her to get ready. She found her phone on a shelf – when had she put it there? – and saw the message from Cal.

Heads up: My daughter wants me to marry you.

Gillian laughed. Even though she did not expect Emily to oppose their relationship it was a relief to know she had received the news well. She'd almost expected Cal to chicken out and conveniently forget to tell Emily about the big change in his life.

She texted back: I'll meet you at the chapel of love at 8 sharp. I have to buy a dress first.

She'd barely hit reply, when Cal's response popped up on her screen: Nah, don't bother. Come naked.

Aren't you confusing the honeymoon with the ceremony?

The church of Cal makes no distinction.

She chuckled and thought about a witty comeback when her phone started ringing in her hand.

"Hiiii", her voice had the distinctive mushy quality of a teenager in love. She rolled her eyes at herself.

"Hey, love, I'm just calling to let you know that I'm about to wrap up things here – that is if Zoë's mum finally runs out of vacation pictures. I'm starting to think that a little accident encounter between the fireplace and the photo album might be required."

"Cal!" She chastised him immediately, "Behave!"

Cal chuckled on the other side, satisfied he'd gotten a rise out of her again, "I'm trying, love. It's hard. It just gets so boring after the first two hundred pictures. What about you, love, are you being a good girl?" He stopped and lowered his voice, "Does Santa have to punish you tonight?"

Gillian's stomach flipped in reaction to his words and a tingly sensation coursed through her veins. How did he do this? "What if I told you I've been a very bad elf today?" She couldn't believe she teased him like that. Could she just hear him swallowing over the phone?

"What have you been doing all day without me?" His curiosity was definitely piqued.

"Reading." She thought about coming clean to Cal about opening his gift and reading the manuscript but his mind had already taken the express train to the gutter.

"Must be a very good romance novel then." She could hear the grin in his voice.

"You have no idea. I'm taking notes for tonight." Gillian lied and Cal groaned. There was silence on the line while Gillian waited for his response and Cal was collecting his thoughts.

Eventually he cleared his voice, which had dropped an octave to his most seductive level, "Can this little elf hope for a powerpoint presentation with a lecture-demo component tonight?"

"If said elf does not keep me waiting too long. Otherwise I may just have to test out my thesis alone."

"Alright, enough." Cal's voice sobered up. "You're giving me a raging hard-on and I have to go back into the living room and sit on a couch with my in-laws."

"I'm sorry, you started it." She didn't seem the least little bit sorry.

"Yeah, yeah, I know but I have to stop before it gets out of hand." Cal admitted, "Anyway, I just called to let you know that Emily and I will be around in about 30 minutes. Thought I'd give you time to prepare and pack an overnight bag…unless you already have." The teasing grin in his voice was back. Of course she had already packed. No way she was going to let him know that. He'd get conceited knowing how desperate she was about seeing him tonight that it was the first thing she did after she came out of the shower.

"Thanks, that's really appreciated."

"Ok, I gotta go before Zoë comes searching after me."

"Sure. I'll see you soon then," Gillian replied and then added just before he hung up, "Cal?"

"Yes?" His eager response came.

There was another moment of silence as Gillian contemplated telling him again. She wanted to tell him about the manuscript and that she understood and she loved him and wanted to grow old with him. She just didn't know how.

"Just."

"Yeah?"

"I miss you." I love you.

She chickened out again. It was probably better that way. What she wanted to tell him was better said in person anyway. This would also give her time to figure out what exactly it was she was going to say to him.

"I miss you, too, love." I love you, too. "I can't wait to see you in half an hour or so."

"I'll be waiting here with bells on."

There was another moment of silence as they were clearly reluctant to end their conversation. It was only when Cal heard someone approaching that they said their final good-byes and disconnected the call.