"What did you make of the Trent kids?" Donovan asked Jones and Sherlock, once they'd finished collecting names and addresses from Edward and had reached the squad car. None of them got into it.

"Boring." Sherlock lit a cigarette. "Well, go on, then, Donovan."

Donovan, visibly disgusted by the rancid puff of smoke that had just drifted into her face, raised her eyebrows. "What?"

"You were a teenage girl, once… I assume."

"Got a feeling you were more of a teenage girl than I ever was," she bit back. Sherlock's lip twitched.

"Caitlin's theatrics," he went on. "What do you make of them?"

She shrugged. "Not sure I'm a very good yardstick," she admitted, folding her arms and leaning against the car. "I probably would have thrown a fit like that over being asked to clean my room when I was that age. You, Jones?"

"I thought she was more upset about her play than anything else," Jones remarked. "Overreacting to what her brother said, 'cause she felt guilty about thinking the same thing. But I'm not real surprised about that. If she hardly even knew Celeste…"

"Yeah. Self-centred kid, but it doesn't mean she knows any more than she's saying," Donovan continued. "That stuff you were talking about, Sherlock. About what hand she wrote with."

"Yes, that had nothing to do with what hand she actually writes with," Sherlock said tersely, heaving a sigh that implied Donovan's remark had lowered his IQ. "Her stepfather. Oh, he's the last word in diligent parenting, but does he know what hand his own stepdaughter writes with? He doesn't. Edward couldn't wait to tell me."

"So?"

"So there's apathy there, if not a downright estrangement. It's not simply that Caitlin's pushed him away while he's done his best to be friends with her. Even if she'd repudiated him, he should have noticed her dominant hand in the years since he married her mother." He took another drag of his cigarette. "So her outburst probably had more to do with the stepfather and the ruined play than anything to do with Celeste Biondi."

"But the play –"

"Oh, the play's a definite link, but not in the way you assume. Who would include such an incriminating quote?"

"Someone who has it in for Lestrade's kid," Jones said. Sherlock shook his head.

"No. Someone who 'has it in' for Matthew Lestrade wouldn't incriminate him in such a clumsy manner – this is a double bluff. Matthew's not stupid enough to quote a play he happens to have lead role in when murdering his girlfriend. Apart from the note, there's almost a complete lack of context for Celeste's death –"

He was interrupted by a sudden, muffled bloop from the direction his coat pocket. Fishing it out, he groaned.

Hi

7:42pm

'Hi'? What the hell was he meant to say to that? Christabel's texts were becoming progressively dimmer and more pointless by the week.

Since the first awkward phone call to Germany three months before, Sherlock had had very little contact with his mysterious half-sister. Certainly, she'd accepted the news surprisingly well, admitting she'd discovered years ago that she had half-brothers in England but had never investigated further. But she never mentioned her parents, beyond briefly affirming that her father was still alive in America. Nor, once she'd established Mycroft's existence beyond doubt, had she ever really mentioned him, either.

She had, however, agreed to contact with Sherlock, which had mainly taken the form of the odd text and email between them.

If Sherlock had anticipated discovering a female version of himself, though, Christabel Mohler was bitterly disappointing. She had inherited her brothers' height and dark hair but, Sherlock noted when she'd sent him a recent photograph of herself, she'd also inherited the beaky nose and closely-set eyes that had been their father's unintentional gift to Mycroft. Sherlock had scanned her photograph over more than once, identifying and discarding features based on whether they came from the Holmes side of her heritage or the unknown, maternal side: Bernier. Eyes and nose: Holmes. Chin and cheekbones: Bernier, or some branch of that family. Comparative height: Holmes. Complexion: Bernier. High facial profile: Holmes. Tendency toward weight gain: probably the Bernier side, since the Holmeses consisted mostly of sinew and bone, and Mycroft's tendency toward pudginess was a combination of appalling personal habits and his mother's genetics.

Then, he'd discovered, the woman's intellectual capacity was quite ordinary, too. She'd had a good education, judging from her fluent writing style in the one or two lengthier emails she'd sent, but she worked a disappointingly ordinary job in Human Resources for the DZ bank. She seemed to have no further ambition in life than to pay the rent on the apartment she shared with her German husband, Carsten, and play mother to two English Springer spaniels.

"Your girlfriend?" Donovan swiped at him.

Sherlock shook himself out of his reverie. Without even dignifying Donovan or Christabel with a response, he shoved the phone back in his coat pocket.

Sitting on Matthew's bed, laptop open on his knees, the reality hit Lestrade like a brickbat: this was a gold mine of character-assassination evidence for a prosecution team.

Over his career, Lestrade had learned that the difference between walking away from a trial and doing time was often what investigators found in your Google search history, or under "My Pictures." It had only been six months before that the tech team had found enough evidence on Peter Duff-Charles' laptop to hand him over for murdering his wife, Annette. Google searches were often the biggest source of incriminating evidence. When a hated spouse or parent was mysteriously murdered, variations on "how to commit a murder" came up with surprising frequency on their shared family computer. And then there were all those times he spent following up false leads, just because of some bonehead stupid enough to publicly say something like, "I swear to God I'll kill you" to someone who, as rotten luck would have it, really had been killed later. The Homicide and Serious Crimes Unit even had a name for those reports: Agatha Christies.

He glanced toward the closed door. I should be down there with him, he thought guiltily. He's my son. I'm supposed to…

He swallowed down on something. No, not now. Now, he was still so angry... angry enough that he knew he'd say things he'd regret, if not give his son a good smack upside the head. Unprotected sex? What the hell had Matthew been thinking?

Probably, not much. Lestrade shoved aside the fact that his own youthful adventures hadn't always been the most careful ones, either. That had been in different times - less than forty actual years, but the world had changed so much since then. Nobody'd had to worry about getting AIDS, and if you got a girl pregnant, even that wasn't the end of the world.

But Celeste Biondi didn't have HIV, and she wasn't going to get pregnant, because she was dead. And Matthew's My Pictures folder wasn't just full of scanned sketches of dragons and architecture… there was also a sizeable stash marked "Artistic Nudes."

And, Lestrade thought as he glanced up from the first scanned charcoal sketch, no prosecutors he'd ever come across ever went into the nuances between "artistic nudes" and "porn". Any sixteen-year-old kid with this on their computer would be immediately labelled a pervert. And most juries would probably go with that, unless they were all artistic-types.

The first few sketches, at least, seemed not to be of Celeste herself. An older woman, probably… in her twenties? Lestrade didn't recognise her from a hole in the wall, but then, Matthew's emphasis hadn't been on an accurate portrayal of her face.

Rubbing his forehead wearily with the palm of his hand, Lestrade looked around the room, trying to think his way out of this one.

Even though Matthew only ever spent a couple of days a week at the house, he'd forged a little home-away-from-home in the spare bedroom. He'd even managed to convince his father to spend one of his weekends off painting the room a dark bottle-green that clashed with the rest of the house but, he'd insisted, went with the claret-coloured bedspread. Matthew had always been neat and organised. The only hint of chaos was at his desk, littered with graphite pencils and the sort of blue paper that made Lestrade think of top-secret submarine plans in old James Bond films. One of his own paintings hung above the bed; something entitled Dark Maria and which seemed, to Lestrade's eyes, to be a meaningless blur of primarily cobalt-blue and black paint. The only other wall decoration was a periodic table on the far wall, which Matthew had gone to all the trouble of framing and putting behind glass.

"Why bother?" his father had asked him, watching him carefully level it months before. "You know all that stuff in your head anyway."

Matthew had looked back at him with, for a second, what had seemed like chilly reproach. "Because," he said, "because it's not just information. It's art."

Lestrade had thought initially that he meant the pretentious sort of university-student art he'd seen on far too many walls. Posters of Che Guevara from kids who had no idea who Che Guevara even was.

Apparently not.

"The way every known element in the universe can be summed up on a table and put on someone's wall," Matthew had insisted. "Don't you think that's art, Dad?"

If Lestrade had been perfectly honest about it, no, he didn't think it was art. But since Matthew could draw anything, and his own stick figures didn't even look like stick figures, perhaps his son had a better grasp on "art" than he did.

So if Matthew thought drawings of nude woman in admittedly tame poses was art, his father believed him. It was just a world of wrong that no jury looked likely to believe him, too.

Julie finally arrived at the house twenty minutes later. Lestrade reluctantly went down to answer the door, and took only a one-second glance at her blotchy face to confirm that she'd been crying on the way there. She was dressed well in a peach-coloured v-neck blouse and white slacks, but her dyed ash-blonde hair had obviously had no more than a brush run through it before she'd left the house. Looking at her tired, haggard face, Lestrade briefly wondered when he'd last seen her without make-up on.

"Is he still here?" she asked wretchedly, without bothering with a more traditional greeting.

"Yeah, of course." He gestured for her to come in. "Through here."

He brought her through the hall and across the kitchen to where Mel now had Matthew sitting on the sofa, nursing a cup of tea. On seeing his mother, he set it absently on the floor and wobbled to his feet. She threw her arms around him.

"Mum, I don't know anything about what happened –"

"We believe you," she said hoarsely. "We believe you, Matthew."

Melissa quietly rose from her spot on the sofa and took Lestrade aside in the doorway for a second. "I'm not going to be difficult about this," she said in his ear.

"I know you're not."

"I'll stay out of it –"

"Yeah, I don't want you to stay out of it." Lestrade took a deep breath. "You asked me before we got engaged," he said with difficulty. "You asked me if you were part of my family or not – and you are. So I don't want you to stay out of it. Besides, you know how this works better than Julie does."

"I've been trying to prep him for what's going to happen if they take him to the station. Letting him know his rights about DNA samples and things."

Lestrade nodded.

"They'd be mad if they didn't at least get him to 'assist with their enquiries.'"

"I know," he said wretchedly. "But I think anything he does or doesn't say is probably the least of his problems just now. There are other types of evidence."

Julie spent the next half an hour nursing successive cups of tea on the sofa next to her son. Hayley, who still had a somewhat strained relationship with her mother, remained upstairs with Jake for the most part. When Lestrade finally coaxed Julie upstairs to the privacy of Matthew's bedroom, he passed Hayley's closed bedroom door; for the first time in his life, he wasn't particularly concerned about what might have been going on behind it. Once he'd ushered Julie into Matthew's bedroom, he shut the door behind her and picked up Matthew's mobile phone, sitting innocuously on the desk where he'd left it.

"Um, I need you to watch this," he muttered, pressing a couple of buttons with his thumb and holding it out to her. "Video… time-stamped last night. Looks like it goes for a couple of minutes."

Julie took it in her hand, looking up at him suspiciously. "Okay," she said slowly. "Why am I looking at it?"

"Because… because I watched the first ten seconds, and I need to know if it's what I think it is," he said, almost desperately. "I can't… look, just, please, look at it."

Julie sank down on the mattress, flicking the video on awkwardly. He watched her as she watched it, but her expression did not change in any way. From the other side of the room, the sound on the video was full of feedback and almost unintelligible, but he noted no sense of urgency or fear in the distorted female voice he heard. When at last the video ceased, Julie cleared her throat.

"Okay," she said, cupping her chin in one hand. "So it's a video of Celeste in some kind of a dirty, shadowy room, with bare floorboards. She's wearing a purple dress, and then she takes it off."

Lestrade groaned mentally. Exactly as he'd thought. "Do they…?"

Julie shook her head. "You can hear Matthew's voice, but you never see him. They don't do anything."

"And she looks… " Lestrade cleared his throat. "She looks happy, willing to be taking her clothes off…?"

"Greg!"

"Julie, will you stop being so bloody naïve about this? This is a murder enquiry, and depending on how hard the prosecutors want to throw the book at him, they've got enough evidence here to charge our son as a sex offender."

Julie startled, as if she'd been given an electric shock. "What?" she demanded. "How is this… she was sixteen, wasn't she?"

"Yes. And it's legal for sixteen-year-old kids to have all the sex they want, but the second one of them starts filming it, they can go down for creating child pornography."

"We need to delete this."

"What? Jesus Christ, Julie, no!" Lestrade snatched the phone out of her hand before she could try. She pulled back in alarm; for a few seconds, they looked at each other in silence.

"The Met employs specialist tech teams for these cases," he explained in much calmer tones. "Nothing ever really gets deleted from a computer or a phone. They can still pull data from this. They can pull data saying that someone deliberately tried to wipe the contents. Do you seriously think they're going to think it was you and not Matthew? And exactly what good is that going to do, anyway?" He looked at the phone in silence for a few seconds, listening to Julie breathing into one hand. "No," he said at last. "No, this is good news."

"Good news?"

"If she looks like she's having the time of her life, it doesn't give much of a reason why Matthew would push her off a roof less than an hour later, does it. The police are going to confiscate this, and his laptop. And we're going to let them take them…"

The sharp knocking sound from downstairs startled both of them. Someone was at the front door… someone from the Met. Lestrade knew that sound. There was a doorbell in plain sight of the front door, but officers were unofficially trained not to use them when they came to make an arrest. Hammering on the door panel created a much more intimidating sound.

"Don't get that!" he called down the staircase. He took the stairs two at a time, only dimly aware of Julie following behind. At last he reached the doorstep and threw the door open, finding Detective Inspector June Merivale on the doorstep.

His shoulders dropped. They'd given the case to Merivale.

DI June Merivale was a fixture of the Yard, having almost ten years active service on Lestrade and most of his contemporaries. A talented detective, she'd more than once been urged to go for DCI, and there were some in the force who felt she could easily become Commissioner. But she had never applied for a promotion, saying she preferred to work her own cases, not hide behind a desk and send detectives out in her place.

Did things her own way, Lestrade knew, but did them. She'd been highly praised eight years before for being able to talk a mentally disturbed woman out of throwing her toddler off the roof of a multistorey carpark in Smithfield. She was not, however, a soft touch, despite her gender, her three children, and her five grandchildren. She was unlikely to do Matthew any favours in the interview room.

"Hi," she said, a little bleakly. She glanced over her shoulder at her sergeant, Alan Peters, who obligingly took a couple of steps back. "I suppose I should go through all the formalities for why we're here."

"You've got a warrant, haven't you." It was not a question.

Merivale nodded. "I'm sorry, Greg," she said. "I'm just doing my job. Let's just get all this cleared up as soon as possible, okay?"

Glancing over his shoulder, Lestrade stepped down and shut the front door behind himself. "Listen, Merivale… June," he corrected himself, remembering her abiding dislike of being addressed by her last name. "Matthew's sixteen years old. His girlfriend just got murdered. And he's… not like other kids his age. Gets upset about little things. I know what your responsibilities are here, and I get that, but I'm asking you for a big favour."

She frowned suspiciously. "Which is what?"

"I want you to let me and Julie put him in the car and take him to the station ourselves, of his own free will."

"Greg-"

"If you arrest him, he's going to completely freak out," he said over the top of her. "Trust me – I've known this kid since he was born. He's… compliant. He likes to please people. Maybe a bit too much. So he's not going to cause you any grief in giving a statement of what happened, and his mother and I will see to that, too. But if you tell him he's under arrest, he may very well go into the kind of meltdown where he can't remember his own name. And what kind of an interview is that going to be? A waste of time."

She shut her eyes and exhaled, thinking this over.

"June," he urged her. "Come on. Please. If this happened to one of your sons – "

"Yeah," she said briefly, opening her eyes and returning to a practical tone of voice. "You know what? I'm thinking 'if Celeste was my daughter.'"

"Either way, you'd want a suspect to give a proper interview, where they can actually be helpful," Lestrade said. "He didn't do this, and we want to give him the best opportunity to prove it."

She glanced back over her shoulder. "I'm sending an officer with you in the car as an escort," she finally said.

"Which one?" he asked, wary. Her sending an officer like DC Pinari along with them wasn't going to help Matthew one bit.

"Sarah Draper. And that's my final offer, Greg."

He scrubbed one hand over his jaw for a second. "Okay," he said. "Okay. Bring Draper in, then. And, uh, June… there's someone else I want you to work with. Please. I'm about to call Sherlock Holmes."