"So what have we got so far?" John asked Sherlock, rubbing his jaw and joining the detective in front of the wall of pictures and notes pertaining to their latest case; a serial killer who kidnapped his victims, tied them up, and proceeded to torture them for seemingly no reason before effectively ending their lives with a bullet straight through the head. The baddest of the bad.

Sherlock, without taking his eyes off the wall, answered John in his deep, monotonous voice.

"We're dealing with a mentally unstable man in his mid to late thirties. Lives alone, no family to speak of, no pets. Works a mundane job, presumably in an office cubicle of some sort. Something unsettling happened in his life recently, something that shook his resolve and triggered the killing spree; he got fired. The torture, while fuelled by uncontrollable rage, is pointless, seeing as the murderer and the victims have no connection whatsoever. There's nothing connecting the victims to each other, either. They differ in age, race, gender, occupation…"

Sherlock trailed off, deep in thought, bouncing slightly on his heels with barely contained excitement. John had long since come to terms with the fact that serial killers for Sherlock were equivalent to Christmas.

"The kidnappings take place at night, likely between nine o'clock and midnight. It takes approximately six hours for the body to be dumped. The killer has been choosing progressively more obvious locations to dispose of his victims, which means he's now begging to be caught. By now we can assume that he's more likely to be through in 3.5 hours, meaning we have less time to catch him," Sherlock grinned. "Oh how I do love a chase!"

"Right. Have you any idea when or where he'll strike again?"

Sherlock's brow furrowed in concentration. He was now pacing in front of the wall of information, eyes squeezed tight as he thought. John could practically hear the gears turning in the sociopath's crazy brain.

Finally he stopped mid pace and looked at John with the tiniest trace of defeat.

"No idea. If I were to guess, I'd say within 32 hours."

John pursed his lips and grabbed his mobile from the cluttered table in the middle of the living room. With a sigh he sent Greg a quick text, summarizing all the information Sherlock just told him. The reply was swift.

Come down here, we've got something.

John quickly snatched his coat from the plush armchair behind him. He glanced at his watch. 9:30. "Listen, Lestrade thinks he's got something and wants us to go down to the station."

Sherlock shook his head, his brown curls flying. "You know I don't leave the flat for anything less than a seven. Text me when you get there."

John rolled his eyes and turned to leave. He was just at the stairs when Sherlock called after him.

"John!" John spun around on his heel to face the taller man. Sherlock seemed to hesitate for the briefest of moments before speaking. "Be careful."

John raised an eyebrow slightly at the sudden concern coming from the man who wasted no time or effort on sentiment, but said nothing. Instead, he gave the consulting detective a small nod and a half smile, then left to fetch a cab. Sherlock peered at John through the window until the doctor was in a cab and out of sight.

He couldn't shake the blossom of worry he suddenly felt. This was ridiculous. It wasn't that late out, and the chances of the killer getting a hold of John were very slim. Very slim indeed. Sherlock argued with himself that there was nothing to be concerned about. John could take care of himself. He was the one with the gun. And Sherlock had much better things to be doing at the moment.

He pushed all emotions to the depths of his Mind Palace and continued to dissect every scrap of information regarding this lunatic of a serial killer.