JOSH HARTNETT and Ariel Donoghue in a scene from Trap. 鈥 IMDB

LONDON 鈥 Josh Hartnett says his role as a shrewd serial killer in filmmaker M. Night Shyamalan鈥檚 new movie Trap marks a departure for him as an actor.

鈥淚t鈥檚 unlike anything else I鈥檝e played, Mr. Hartnett, who has starred in films such as Black Hawk Down, Lucky Number Slevin, Pearl Harbor, and The Virgin Suicides, said at the London premiere of Trap on Monday.

鈥淗onestly, taking on this character wouldn鈥檛 have been possible had it not been for Night, because if you鈥檙e going to take on something this wild and this out there, you need somebody who you really trust behind the camera,鈥 the American actor said.

鈥淎nd another thing is, I just always like a challenge.鈥

In Trap Mr. Hartnett plays Cooper, who takes his teenage daughter to a pop concert that turns out to be an elaborate police entrapment operation set up to catch a serial killer 鈥 who turns out to be Cooper. The psychological thriller was written, directed, and produced by Mr. Shyamalan, who is known for his unique plot twists.

鈥淚 try to create something really hyper original in the marketplace so I can compete,鈥 said Mr. Shyamalan, whose credits include The Sixth Sense, Signs, and Split.

That originality means the work 鈥渟ticks with you. The idea here was like a concert and a thriller together.鈥

Getting into the mindset of the character involved reading about psychopathy and sociopathy and long discussions with Mr. Shyamalan about the tone they wanted the character and the movie to take, Mr. Hartnett said.

The result was another career high point, said Mr. Hartnett, 46, who started acting in the late 1990s and whose recent work includes roles in Christopher Nolan鈥檚 Oppenheimer and Guy Ritchie鈥檚 Wrath of Man as well as parts in TV series Black Mirror and The Bear.

Trap is out in cinemas globally in August. 鈥 Reuters