Madhouse

Madhouse is a 2004 slasher film, directed and co-written by William Butler and starring Joshua Leonard, Jordan Ladd, Natasha Lyonne, Lance Henriksen, and Mark Holton. Its plot follows an intern who uncovers a series of murders at a rural psychiatric hospital. It’s an international co-production film between the United States, Romania and the United Kingdom.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.