Obsessed is a 2009 American thriller film directed by Steve Shill. The Rainforest Films production stars Idris Elba, Beyoncé, and Ali Larter. Obsessed tells the story of Lisa, an office temp played by Larter, who develops romantic feelings for her boss, Derek Charles (Elba), and repeatedly attempts to seduce him. Derek's wife, Sharon (Beyoncé), learns of Lisa's obsessive behavior, and suspects an affair. Screen Gems president Clint Culpepper conceived the basic idea of Obsessed, which was then developed by writer David Loughery, allocated a production budget of $20 million, and filmed in the summer of 2008. Obsessed was inspired by the work of directors Roman Polanski and Alfred Hitchcock, and its score was written by James Dooley. Lisa and Sharon were dressed in contrasting styles to reinforce their conflicting characters. Obsessed opened in US theaters on April 24, 2009, and UK theaters on May 29, 2009, and was distributed by Screen Gems.