Josh Hartnett studied serial killers to prepare for new movie Trap

In M. Night Shyamalan's upcoming psychological thriller the Pearl Harbor actor plays Cooper, a serial killer known as The Butcher. Cooper takes his daughter to a pop concert and eventually realises the event is a trap set by police to catch him. To prepare for the role, Hartnett read "all the books" to get into the mindset of a serial killer. "You've got to know who you're playing and so getting into the darkness of a serial killer's mind. There are plenty of books on these people that exist now and why they did what they did.”