The bombing of a large ferry has just occurred in New Orleans, so hometown AFT agent Doug Carlin (DENZEL WASHINGTON) is immediately on the scene. Meeting FBI agent Pryzwarra (VAL KILMER) and his boss Jack McCready (BRUCE GREENWOOD), Doug seeks out the small details for clues, all of which leads him to a morgue where he views the body of Claire Kuchever (PAULA PATTON). She's seemingly one of the ferry victims, but Doug becomes suspicious when he hears her body was reported before the explosion.
Seeing how Doug is with deciphering clues, Pryzwarra recruits him to be part of their investigatory team. It seems the government has found a way to look into the immediate past, and with technicians including Dr. Alexander Denny (ADAM GOLDBERG) and Shanti (ERIKA ALEXANDER) manning the consoles, they might be able to spot the killer before he commits the already executed attack.
Thinking Claire is the key, Doug has them focus on surveillance footage of her and her apartment, an act that intrigues him even more when he realizes a previous phone message he got from a work associate, Kevin Donnelly (MARK PHINNEY), was from Claire, someone he doesn't previously know, or so he thinks.
Accordingly, Doug becomes obsessed with solving the case, particularly as he becomes fixated on Paula and having heard that his partner, Larry Minuti (MATT CRAVEN), might have been on the ferry that will blow up again in the past. Once they identify the bomber as Carroll Oerstadt (JIM CAVIEZEL), it's a race against time to stop him from repeating the act in the past, all while Doug and the rest aren't even sure they can have such an effect.