Director Christopher Nolan's psychological thriller, which explores the architecture of the mind, took 5.9 million pounds, according to Screen International on Tuesday. "Shrek Forever After" held onto second spot three weeks after its release, with the latest instalment of the Twilight series in third. Fourth, down one, was sci-fi film "Predators", while Russell Brand in "Get Him to the Greek" slipped from fourth place to fifth. Thriller comedy "Killers", featuring Ashton Kutcher and Katherine Heigl dropped to sixth from fifth. "Heartbreaker", a romantic comedy set in France, stayed in seventh. In its eighth week on UK screens, "Sex and the City 2" was down two at eight, just above "Leaving", up three from 12. Classical music comedy "The Concert" made its debut at 10.