While attending a biotechnology summit in Berlin with his wife Liz (January Jones), Dr. Martin Harris (Liam Neeson) is involved in a violent car wreck that leaves him in a coma for four days. He wakes up, disoriented and confused, and quickly realizes his memory of the accident and the events that preceded it aren't entirely clear. Strangely though, no one -- not even his wife -- seems to have been looking for him in the four days that he was missing. Returning to his hotel, he's soon shocked to discover Liz doesn't recognize him at all. In fact, she's married to a completely different man (Aidan Quinn) who claims he's the real Dr. Martin Harris. With no way to prove his identity and few clues at his disposal, Harris tracks down the female cab driver (Diane Kruger) whose driving landed him in the hospital and turns to an Stasi agent-turned-private detective (Bruno Ganz) in an effort to make sense of it all. As the stakes are raised and assassins come filing out of the woodwork, an old friend (Frank Langella) arrives to help identify the real Dr. Harris.