When patrolman Rick Newhouse comes under fire, he requests backup and two patrol cars are dispatched. Both arrive too late and Newhouse is killed. The subsequent investigation clears everyone involved but Detectives Logan and Briscoe smell a rat and get Captain Cragen's permission to investigate on their own. They find that both patrol cars arrived at the scene at virtually the same time though one was 20 blocks further away when they set out. When a passerby says he he saw a patrol car sitting around the corner while the shooting was going on, they know Newhouse was left on his own. What they find is that Newhouse was gay and his fellow officers were giving him a hard time about it making it clear he wasn't welcome in their precinct. ADA Stone charges three cops with second degree murder though he knows the odds are stacked against getting a conviction.
—garykmcd