Submerged

Submerged is a 2005 American-Bulgarian action film starring Steven Seagal as a mercenary who is freed from prison in order to rescue some captured commandos, only to run across a sinister brainwashing plot to turn innocent people- including the rescued commandos- into mindless assassins. The film costars Vinnie Jones, Christine Adams, and Alison King.

Plot Summary
When the U.S. ambassador to Uruguay is murdered by her own guards, when scientist Dr. Chappell (Adams) suspects mind control, the U.S. sends a team of commandos to investigate, but they are ambushed and taken prisoner. To save them, the government calls upon Chris Kody (Seagal), a mercenary sitting in a military prison because of his less-than-legal approach to stopping terrorist attacks. Kody is offered freedom in exchange for saving the commandos, but unfortunately the men have all been brainwashed by the evil Dr. Lehder (Nick Brimble), and after the team steals a submarine to escape, the brainwashed soldiers try to kill them and sink the sub. The team manages to escape just in time.

Back on land, the team discovers that Ledher plans to assassinate the President of Uruguay using a number of brainwashed civilians, including the President's girlfriend (Victoria Iovcheva) and the conductor of the symphony he'll be attending. Kody, Henry (Jones), Damita (King), and Luis (Stephen Da Costa) storm the opera house and manage to stop all of the triggered assassins before they can complete their mission.

Kody fights his way to Lehder's lab only to find that the doctor has been murdered by the real mastermind, the traitor Fletcher (William Hope). Kody and Fletcher battle, Fletcher is killed, and the lab is destroyed.

Later, Kody shares a celebratory drink with Luis, Damita, and Chappell. Unbeknownst to them, Chappell was also brainwashed by Lehder, and is now a ticking time bomb.