A/N: Hello! Welcome to my new story! I won't talk your ear off; I just wanted to let you know ahead of time that: 1) This is an AU which takes place during Sherlock's time at university. As such, it does not contain any season 4 spoilers but does include cocaine use. 2) I am American, and while I try my best to make the characters sound like themselves, certain slang/colloquial words may be incorrect. I apologize and if you notice any glaring ones, feel free to let me know and I'll try to fix it. And of course, feel free to leave any other questions/comments/criticism in a review! Enjoy!

Sherlock Holmes was not merely high on the night that Zachary Wells drowned in the local lake. No, he was, in fact, so far beyond "high;" he was soaring on different planes of existence, feeling colors, lost in spiraling thoughts. The word "high" did not begin to cover how supremely fucked-up he was.

He was walking back to his residence hall, but stopped near the lake, his drug-addled brain trying to convince him that it was a good idea to go for a spontaneous midnight swim alone in the dark and fully dressed. He might have done it, too, except that he saw two people already standing on the edge of the water. Sherlock, being rather averse to social interaction even when he had the mental capacity to behave like a law-abiding citizen, decided to keep his distance.

He was, however, a people-watcher by nature and stayed a minute to flex his deductive muscles. They were both male, and though such a rendezvous initially implied lovers, their demeanors were tense and suggested they were fighting. Sherlock could only see their shadows, but could tell from the shorter man's stance that he was a strong but unaggressive man…

Sherlock's eyebrows raised when the man suddenly shoved the taller one into the water. Had he been wrong? Was the short man violent by nature?

It occurred to him then that he hadn't yet heard voices. He was some distance away, but if the two fighting men had been yelling, he would have heard them clearly. The fight was clearly escalating- where was the yelling?

At first, Sherlock was comforted when he saw the shorter man crouch down next to the water, extending his arm out to the other man. "See," thought Sherlock, "the violent outburst was unlike him, because you were right about him, because you always are. They're making up now. He must be apologizing, pulling him out of the water. They'll go back to their boring lives."

Except that the second man didn't emerge from the water as the seconds passed. The first man's hand was reaching out.

And Sherlock would blame it on the cocaine that it took him this long to realize that the hand the shorter man was holding out was not seeking the other's hand but holding his head down under the water.

And maybe, if not for the cocaine, Sherlock would have done something about it rather than just standing back and thinking about how interesting the whole thing was. But instead, he watched the surprisingly still scene for a few more minutes, until the man by the lake stood up and walked away. Sherlock could see no evidence of the body on the surface of the water yet, but it was shallow- once the search started, it wouldn't take long.

The man- the killer- did not walk in Sherlock's direction as he left, nor did he turn to look at him. But when he passed through the moonlight, Sherlock was able to see a glimpse of his face. It was no one he recognized. He was nice-looking but not in a committed relationship, Sherlock deduced. Short blonde hair; had played a sport in high school but not anymore. It was hard to get much more about him from this distance. He didn't appear to be on drugs or alcohol, but he did not have the anger or fear one might expect on the face of someone who had just killed a man either. If anything, he seemed anxious, looking around as though he was unsure what to do next. Then he was gone, running back into the darkness, and Sherlock turned the other way. At home, he lay in bed riding his high until he crashed into a deep sleep.

When he woke up in the morning, he remembered nothing of what he'd seen.

Sherlock arrived at the station on Monday with a clear head and a working dose of cocaine running through his bloodstream. Saturday he'd spent getting high, Sunday he'd spent coming down, and he was glad to have been called onto a case- he was getting bored.

He strode over to the desk where Lestrade was working and rapped his knuckles against the surface.

Lestrade glanced up. "Not now, Sherlock. I have paperwork to sign."

"You requested my help, Lestrade- if I am inconveniencing you I can return to my studies."

"Oh, don't throw a fit. It'll only take a minute. Some kid drowned in the lake on Saturday night."

Memories flooded Sherlock- he hadn't deleted them, but they had been lost in the haze of his high. Even now, they came back in distant flashes. A crouching shadow, arm held out over the water, pressing a head down. That shadow turning to the light- but that face was so blurry. "Drowned?" he repeated.

"Yeah. Zachary Wells. Went to your university- you know him?"

"No…" I think I witnessed his murder while high on cocaine didn't seem like a viable answer. "How did he drown?"

"He had too much to drink and thought he'd go for a swim. I have to sign off that no foul play is suspected."

What to do now? Any confession of what he saw would quickly lead to questions he couldn't answer- sure, he could claim he was 'out for a walk' but there was no reason for a sober man, especially one who is known to work with law enforcement, to not report such a crime right away.

"You can do it later. This is boring," Sherlock tried. "Are you going to update me on the murder case or not?"

Lestrade sighed but set his pen down. "Callie Rogers, stabbed in her dorm room on Saturday between 10 and 11 pm, most likely sometime around 10:15."

"How on Earth would you know that specifically?"

Lestrade turned to his computer and showed Sherlock some security footage, a mere second-long clip of a door flying open and then slamming shut. The way the door opened into the hall, swinging towards the camera, made it impossible to see the person standing behind it. "This happened at 10:15 exactly. We believe that it may show Callie trying to escape- but…"

"But she is caught and killed before she can even scream for help." Sherlock said bluntly. He had no time for Lestrade's euphemisms- his curiosity had been captured. Not just by this case, but by this foggy memory coming back to him. He could remember getting home at 10:30 that night, and he lived 15-20 minutes away from the lake depending on his pace. Had two murders truly taken place within minutes of each other? What did that mean? But of course, Lestrade interrupted his thoughts.

"There's no audio- what makes you think she didn't scream?"

"Well it's a bloody dorm hall Lestrade, if she'd screamed someone would have come. Look at the video- no one even walks into the hall to investigate."

"Her best friend found her on Sunday morning," Lestrade admitted. "She didn't have a roommate. So you're probably right."

"Of course I'm right," Sherlock scoffed quietly. "Is there any particular reason you called me in for this case?"

"One of them locked-door cases, isn't it? There's only one door in and no one comes in or out anywhere near the time of the murder."

"Did the victim live so high up that a ladder wouldn't reach her window?"

"First floor, actually, but the windows don't open more than a few centimeters. What do you make of that?"

Lestrade clearly expected Sherlock to be stymied, so Sherlock maybe found a little pleasure in keeping his face passive and saying, "The murderer was either stalking Callie or, much more likely, knew her. Is there a suspect fitting that description at this time?"

"Uh… yeah. There's a friend of hers in the interrogation room right now. Sent her threatening text messages the night of the attack. How do you- "

"He accessed her room prior to the murder. Check further back in the tapes, see who had visited her recently, and while you're at it have someone check that they haven't been tampered with. It would be so boring if this were just an ordinary killer who knew how to remove himself from the security footage. In the meantime, I will talk to this suspect."

He walked briskly to the interrogation room, where a man sat at the table facing the opposite wall. He turned when he heard Sherlock come through the door.

That face… He remembered it clearly now, that last look at the man in the moonlight, the man who had drowned Zachary Wells. It was him, and he was sitting here suspected of murdering someone else- someone, Sherlock remembered, that he couldn't possibly have murdered because he was miles away, by the lake…

Thrown off his game at last, Sherlock cleared his throat, determined not to lose his composure. "My name is Sherlock Holmes, I'm here to ask you a few questions about what happened on Saturday night. Let's start with your name."

The man seemed nervous, but attempted a smile and held out his hand to shake.

"John Watson."