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.

He then seeks help from Nurse Herfort's friend, private investigator and former Stasi agent Ernst Jürgen. Martin's only clues are his notebook and Gina, who works at a diner after being fired from the taxicab company since the incident. While Martin attempts to persuade Gina into helping him clear up his identity problem, Jürgen digs up information related to Martin and the biotechnology summit. He discovers that the summit is to be attended by Prince Shada of Saudi Arabia, who is funding a secret project headed by Bressler. Prince Shada has survived numerous assassination attempts from extremists in his own country, and Jürgen suspects that Martin's identity theft may be another attempt at taking the Prince's life. Meanwhile, Smith and another assassin, Jones, attempt to eliminate Martin and Gina, but the couple escape after a fight at her apartment, in which Gina kills Smith, and a car chase. Martin looks at his notebook and sees a set of numbers written by his spouse. The numbers correspond to words found on specific pages of the notebook, which appear as secret codes. Using the schedule written on the notebook, Martin confronts Liz, who tells him that he left his briefcase at the airport. Meanwhile, Jürgen receives Cole at his office, and discovers that both Cole and Martin are members of a secret squad of mercenaries known as "Section 15".

–from wikipedia