Unknown (2011)

Unknown is a 2011 psychological thriller film directed by Jaume Collet-Serra, starring Liam Neeson, Diane Kruger, January Jones, Aidan Quinn, Bruno Ganz, and Frank Langella. The film is based on the 2003 French novel published in English as Out of My Head, by Didier Van Cauwelaert.

Plot: Dr. Martin Harris and his wife Liz arrive in Berlin for a biotechnology summit. However, upon arriving at Hotel Adlon, Martin realizes his briefcase was left at the airport. He takes a taxicab driven by Gina, but on the way to the airport, the cab crashes off a bridge into the river. Martin is knocked unconscious upon impact, but Gina saves him from drowning before fleeing from the scene to avoid the police, since she is an illegal immigrant from Bosnia. On Thanksgiving day, Martin regains consciousness at the hospital after being in a coma for four days.

Martin returns to his hotel, only to discover another man with his wife, who claims she doesn't know him. He attempts to contact his old colleague Prof. Rodney Cole, who is unavailable due to Thanksgiving in the United States. Martin then heads to the office of Prof. Leo Bressler, whom he is scheduled to meet that day. However, he sees the impostor, "Martin B", already in a meeting with Bressler. As Martin attempts to prove his identity, Martin B shows him his ID and family photo – both of which have Martin's name, only with his face replaced by that of the impostor. Disillusioned by the identity crisis, Martin falls unconscious and finds himself back at the hospital. Smith (Olivier Schneider), an assassin sent to target him, kills Nurse Gretchen Herfort, but Martin escapes.