A/N: I own nothing. Credit goes to Ceridwyn for being my beta once again.

This idea spawned partly from the speed-dating promo and an interesting factoid I spied on Twitter.

Chapter One – En Route

Rivulets of rainwater streamed downhill in front of Maura Isles' Beacon Hill townhouse. Reflected streetlights twinkled like Christmas lights on the ground as the Medical Examiner hurriedly navigated the short distance from her front door to the taxi waiting at the kerbside.

The uneven paving stone of the sidewalk had created several large puddles of standing water but the blonde skipped over and side-stepped them with a dancer's grace.

Swiftly reaching the rear passenger door without so much as a splash, she folded down the small umbrella that had been protecting her hair and make-up from the never-ending downpour. Once situated in the backseat, she closed the door quickly before settling her purse on the seat beside her.

Huffing in annoyance at the weather, the petite blonde swept some loose curls out of her face as the driver peered through the rear view mirror. Her eyes met his only a second before she addressed him, politely requesting her destination with a warm smile.

"Arnaud's Bistro, please. It's down by Coolidge Corner Station."

The burly driver acknowledged her request with a nod, his kind eyes crinkling at the corners.

She couldn't see his mouth in the mirror but assumed her smile had been returned.

"Sure thing," he said, his deep voice rumbling almost as low as the engine.

Happy that he didn't seem to want to converse further, Maura breathed deeply and turned to look out the window. As the taxi pulled away she contemplated the potential of tonight's date, the man she would be meeting, and the unknown quality of the restaurant he had chosen.

She had voiced her uncertainty to him about the venue, with the utmost diplomacy, more than once, but he wouldn't be swayed. A 'recommendation from a friend' was all well and good but, by her very nature, Maura put more stock in the unbiased and honest reviews of its most recent patrons. She hadn't dined at this particular bistro before but had researched it online and the feedback was less than stellar. Let's hope the quality of the company makes up for it.

They'd barely been travelling for more than a minute when her cell phone rang from deep within the confines of her purse and she rummaged for it with a small amount of relief. If the driver had been thinking about shooting the breeze, he wouldn't have the opportunity now.

It wasn't difficult to imagine the cabbie's attempt at starting a conversation. It would be a carbon copy of every other social exchange she'd had this week outside of the precinct.

'Can you believe this rain, huh?! It'll be like this for another few days they reckon.'

Mm-hmm. Not exactly a stimulating discussion.

It had been raining non-stop for over a week and everyone was sick of it, the doctor included. The weather stations were all saying the same thing. It was all anyone could talk about and it was rapidly dampening the doctor's usually cheery mood. If her date happened to be interested in a dialogue on meteorological phenomena and atmospheric chemistry she would be more than happy to oblige, but for now she was safe from the discomfort of small talk.

The screen was bright within the darkness of the taxi's interior as Maura pulled it from her purse, lighting up the blonde's face with a bluish light. She swiped at the screen to answer the call. It was Jane.

Maura couldn't contain a smile as she spoke warmly, "Hi, Jane."

The detective sounded highly strung and a little winded, "Maura, where are you?"

The doctor's eyebrows drew together slightly, hoping this wasn't a work-related call but suspecting as much from her friend's tone, "I'm in a cab. I have a date tonight, remember."

The brunette wasn't convincing at all as she tried to be nonchalant, her voice higher than usual, "Oh, yeah, was that tonight?"

The doctor murmured, unimpressed, her lips forming a tight line, "Mm-hmm." You knew fine well that was tonight. Maura heard the familiar sound of Jane's car door slam before the sound of the connection changed. Speakerphone. Good girl.

Jane's car engine fired up and rumbled away in the background as she continued undeterred, "Well anyway, I was thinking some more about the case. We're not getting anywhere and it's driving me crazy, but what if we're just not looking at the evidence the right way?"

Maura's brow furrowed and she shook her head, "I'm not sure what you mean. You know how evidence processing works -"

"I know, I know, but hear me out…"

Jane was like a dog with a bone on most cases and this one was no different. She wasn't going to let it go and Maura knew if she wanted to enjoy her evening without further interruption she might as well humour the detective now while she had the chance. "Go on."

"We know the killer was someone at that bar and we took prints from all the glasses and bottles that were used, but we didn't get any matches to the partial on the knife. We also know we have at least one used glass with no prints…"

The fingers of Maura's left hand were rubbing softly across her forehead as she stared into her lap, "There are many reasons why a used glass might not have useable prints and we sent off DNA samples for analysis to -"

"Again, I know that. But there were so many places at the scene that should have had prints and there was no indication that anything was wiped clean."

The doctor could picture Jane gesturing wildly with one hand as she spoke, exactly the way she would if Maura were seated next to her. Always so passionate. "You'll have to tell me where you're going with this, Jane."

"Okay," she paused for a breath, "what if… the killer doesn't have any fingerprints?"

Maura was silent. It wasn't the craziest theory she'd ever heard a homicide detective come up with but it was borderline desperate. Not dismissing the idea without consideration, Maura's lack of response prompted Jane to fill in some blanks.

"Let's just say, theoretically of course, that the partial belongs to whoever last used the knife and not the killer. The killer might be counting on us pinning this on someone else, it could be a deliberate framing, or... it could just be coincidence there was a partial print on the weapon at all."

Maura raised her head to check the taxi's progress, surveying dark surroundings through the rain spattered window. She closed her eyes for a brief moment and tried to relax the tense corrugator muscles in her brow, "Jane, the probability of that is so low I can't even -" Maura gestured with her free hand in frustration as her impressive brain tried and failed to calculate a number of such magnitude at a second's notice.

Jane wasn't waiting around for Maura to finish that sentence. She didn't need to know how many million to one the odds were against her being right, "But not impossible, right? You told me about that study, from, er… Serbia or something, I forget, but the guy had ammo… ammo…" Jane wiggled her fingers as she spoke, curling them over and over, as if Maura could see her and the motion alone would coax out of the doctor the term that was on the tip of the detective's tongue, "…ammohieroglyph…something -"

"Oh. Adermatoglyphia!" The blonde almost giggled. The detective's attempts at pronouncing unfamiliar scientific terms were always a little comical but the doctor would give her an A for effort this time. And she really does listen to me! "Mmm… studied in Switzerland," Maura stated thoughtfully. "Those affected have a lack of epidermal ridges."

Jane switched hands on the steering wheel in order to snap her left thumb and finger, ecstatic that her genius friend retained almost everything she ever read, before pointing her index finger enthusiastically at the cell phone strapped to the centre console, "YES, that!"

Maura sighed softly. It was a massive leap from the common occurrence of not finding a useable print to having found a suspect that had no prints. "It's an extremely rare gene mutation, Jane."

"Aaa-and…" the detective drew out dramatically, "…a great party trick to get away with murder!"

Maura saw no good reason to work on this very suspect theory tonight. She had better things to do. Fingers crossed. "No fingerprints doesn't mean no sweat glands. He'll still leave DNA behind even if you're right. We just have to wait for the results of the swabs and we could have a match in a day or two."

"But, Maura-aaa…"

"But nothing, Jane. I know you. You're itching to get back to the crime lab right now in order to harass my staff and get them to hurry the tests, which you know they can't do, and you'd probably drag me along with you!"

"Yeah, so? We're a team." Jane whined before pounding her car's horn and yelling loudly, "It's just a bit of rain, idiot. Get a move on!"

The blonde smiled to herself. She could be, and quite often was, talked into many things by her best friend. Those deep brown puppy dog eyes don't help. But tonight she wasn't budging. Checking the brunette was still on the line after her outburst, Maura queried, "Jane?"

"Yeah?"

"We will still be a team tomorrow morning, if this really can't wait. But like I said, I have a date."

Jane huffed. "Okay, fine."

Maura rolled her eyes. "You're already on your way there, aren't you?" She shook her head at her friend's behaviour. Unbelievable.

Jane shoved a hand underneath her hair and rubbed at the back of her neck, momentarily uncomfortable and a little thrown, "No. I, er… I happen to have a date myself actually."

Maura heard a lie, but without being able to see the minute facial muscle movements that would be the brunette's tell, she wasn't one hundred percent sure. She went with what she knew, "I can hear you driving, Jane."

Jane scoffed, a little offended, "So? Maybe I thought I'd save on cab fare and be fresh as a daisy in the morning in order to get back on the case if I drove and didn't drink tonight."

She's bluffing. Maura matched Jane's tone and vocal pitch, "Or, maybe you were trying to come up with ways to get out of meeting a man your mother no doubt set you up with, and being suddenly and conveniently forced back to work en route in your patrol car was your best bet?"

Jane sighed loudly. Busted. "Alright, you got me."

"You need to relax, Jane. Take tonight to decompress. Enjoy yourself." It was advice she would be taking herself, even if her friend refused to comply. "The lab and the evidence will still be there tomorrow. I'll do some research in the morning and meet you there at lunch."

Jane decided not to argue with the doctor's recommended prescription lest it turn into a much longer conversation involving questions about the last time the brunette had had sex. Those happen way too often, no need to encourage her! "Okay. Thanks, Doc."

Maura purred. "No problem, Detective."

Jane had pulled to a stop in a public parking lot. She'd have to run the next block to the restaurant with her long coat pulled over her head to have any chance of not getting soaked to the skin. "Right, well, see you tomorrow, Maura."

Maura's cab was just pulling to a stop outside the restaurant. She handed the driver several folded bills, mouthed a silent 'thank you' and placed her billfold back into her purse. She perched the cellphone between her ear and shoulder as she exited the vehicle and quickly entered the restaurant, "I'll text you. Goodnight Jane."

Jane ended the call and slumped in her seat, staring out the windshield and into the darkness as the rain continued to shower the windows. A shiver ran its way throughout the length of her body and goose pimples erupted all over her skin. She couldn't have imagined a more miserable evening for a date. The damp permeated everything, her mood included. This better be worth it!

The brunette exited her vehicle with a frustrated groan. She wrapped her coat tightly around herself, the low hem brushing her bare calves, and tried not to shiver against the cold.

The restaurant wasn't far but as she left the relative darkness of the parking lot, with its scarce overhead lighting, her vision fought the encroaching pitch-blackness of an unlit side street. Desperate to cross, to reach her destination illuminated half a block up, she hurried. Taking her gaze upward from the street surface to check for any oncoming traffic, she stepped from the kerb straight into a puddle.

"Oh, come ON!" she shouted, head and hands turned towards the sky.

Reaching the restaurant entrance, Jane took a second to compose herself. Shaking water droplets from her dampened head, she looked down at her feet. Four-inch heels, unused except for several court appearances, were covered in wet patches. There were a few spots of something dark splashed across one ankle and her toes squeaked and squelched with moisture. It was typical of her luck with dates. Just typical. I bet Maura doesn't have to put up with this shit!