2 hours earlier

John Carter sighed as he sat down on one of the few available seats on the El train. He rolled his head from side to side, trying to work the kinks out of his neck. Then he leaned back against the unyielding plastic seat, glancing around the carriage without really seeing any of his fellow passengers before focusing his gaze out the window opposite.

Carter had not admitted it to Kerry, and had even grumbled as he left, but he was glad she had sent him home. Despite all his determined reassurances to Benton, the resident suspected that he had returned to work a little too soon after the shooting. He went home exhausted every night, and getting up in the mornings was becoming more and more difficult. Added to the daily stress of the job was the need to show Benton that he was perfectly well every morning when the surgeon appeared at his apartment, and that he was not overly tired every evening on the way home. He was beginning to doubt the wisdom of turning down Gamma's welcome home present. And he had already begun berating himself over rejecting it within Benton's hearing. It wasn't that he didn't appreciate the surgeon's driving him to and from work, or that he didn't enjoy their daily carpool conversations… It was just that Benton's guilt was still an almost palpable force, and that meant Carter had to project an extra layer of well-being whenever they were together. Besides which, the surgeon was proving to be a mother hen of previously unimaginable proportions.

Remembering that he had yet to contact the surgeon, Carter pulled out his cell phone. He dialed Benton's cell number, sitting up slightly as he got a response. He settled back again when he recognized the generic automated message.

"Hi, Dr Benton, it's me," John paused a moment, then clarified, "Carter." He briefly wondered when he had started thinking of himself by his last name. "I tried to call you upstairs before I left but I guess you're in surgery or something." And thank God for that, thought Carter, knowing he had escaped a stern lecture on over-doing things. "I just wanted to let you know that I'm heading home early so you don't have to give me a ride. I'm on the - "

BANG!

Carter recoiled at the sound, so close, so unexpected, so strangely and horribly familiar. Without any conscious thought, in one fluid motion, he ended the call and slipped the cell phone into his pocket. It had disappeared from sight even before the first hysterical scream of realization echoed through the carriage, even before the person sitting directly across from him slid off the seat and landed in a shapeless heap on the floor.

It required a deliberate effort for Carter not to rush to the fallen man's side. If the gunman hadn't been standing over the body, prodding it with a toe, the doctor probably would have already been kneeling in the growing pool of blood. But the man was evidently curious about the consequences of his actions, and continued to nudge the inert form with his right foot from different angles.

Carter watched with gritted teeth, holding himself back, knowing that if he tried to help he would most likely get a bullet in the brain. The body lay in a position that made it impossible for Carter to establish if the shot man was even breathing, or where the bullet had entered, or if it had exited. Carter watched the gunman carefully, hoping to see some sign of worry, if not remorse. There was none.

After the first shocked screams tapered off, a stunned near-quiet fell over the carriage, interrupted only by a few disjointed murmurs, some whimpering. A baby was crying noisily, and its mother's desperate attempts to shush it were having no effect. The gunman lifted his head from his callous examination, frowning deeply as he sought out the source of the sound. He started to move towards them, accidentally brushing against the downed man's back with his leg.

Something thudded to the floor.

" - you - opy?"

The gunman froze, eyes narrowing. "Shut up!" he shouted at everyone, kneeling beside the body. "Shut up now!" He raised the weapon over his head and fired a round into the ceiling. The general whimpering hushed, then ceased. The mother clamped her hand down on over her baby's mouth, cradling it against her chest in mute apology.

In the silence, the small, disembodied, tinny-sounding radio voice filled the carriage. "Williams, do you copy? Come in."

"Fuck! He's a fucking narc!" The man surveyed the policeman's body with a terrified rage. He stood up and leaned towards the window, peering at the next stop; the people on either side of the now-empty seat cowered back from him. "Oh, shit, shit, shit!" He slammed the gun sideways against the window with a resounding crack which caused everyone to jump, then he hastily withdrew to the center of the aisle.

Carter shifted his gaze to the approaching stop. There were at least ten uniformed policemen gathered at the edge of platform, with more covering the exits of the station. If they were trying to conceal their firearms, they were doing an extremely poor job of it.

Before him, the gunman paced rapidly, nervously, two quick steps in each direction, striding over the policeman's unmoving body as though it were part of the floor, thumping his forehead with the butt of his gun. Then, abruptly, he stopped, jaw clenched, eyes hard, dark and unreadable. With a sinking sense of the inevitable, Carter watched him reach for the emergency alarm.

The train ground to a shrieking halt.

Part 2