In the course of a 40-year career, quintuple-threat Hampton has toiled away as a Tony-winning librettist (“Sunset Boulevard”) and Oscar-winning screenwriter (“Dangerous Liaisons”) as well as a playwright, translator and film director.

How does he decide whether a story is righter for stage or film? “It’s hard to explain, but I feel it very strongly,” he says. “It’s a matter of instinct, really.”

His instinct told him that Ian McEwan’s bestseller “Atonement” was a pic he had to write: “I really admired the book and lobbied for the job.” Like several of his plays, including “Total Eclipse,” “it contemplates the responsibilities and dangers and consolations of being a writer. It’s also about the power of guilt and creativity. You never know whether what the child has done is an act of malice or a simple mistake or a combination of the two. But no matter what, it’s marked her life — it’s a primal wound that’s made her an artist.”

Hampton earned worldwide acclaim for “Liaisons” on the stage and screen. Pic version “was exactly the film we wanted to make,” despite being in a race to the finish line with Milos Forman’s similar-themed “Valmont.” “They gave us the money and said, ‘Go make it. Just make sure it gets finished first.’ “