Screening at the 42nd New York Film Festival, Lincoln Center's Alice Tully Hall, October 10, 9:30 pm.

This last installment in the Infernal Affairs trilogy directed by Andrew Lau contains many satisfying answers to questions that have lingered after the first two police dramas. They are delivered through flashbacks.

Following his violent beating of a criminal, Yan (Tony Leung) is ordered by his boss Wong (Anthony Wong) to see a psychiatrist. It turns out that she (Kelly Chan) has a soothing effect on him: her office is the only place that he can sleep. She wonders about his work, and he wants to tell her the truth.

Meanwhile, his nemesis, Inspector Lau (Andy Lau), is also falling apart after years of fearing that he will be exposed as the Triads mole in the police department. His wife has left him, and he wants to leave behind his past and just be a good cop. But Superintendent Yeung (Leon Lai) is on his back. He wonders whether he is the lawbreaker who's killing Sam's other moles in the police department.

Like a good espionage film, this last installment reveals the desperate lengths men will go to protect their covers and to survive the infernal agonies of fear, paranoia, and lack of trust. Who can you trust in a world where everyone is not what they seem?