The fourth "Mission: Impossible" outing has a much lighter tone, thanks to Pixar animation ace Brad Bird, the studio's first director to tackle live action. His fresh touch gives breathless energy, tremendous excitement and, above all, humor to what could have been a wearying genre exercise. The plot may be perfunctory (again with the stolen nuclear-launch codes?) but Bird has choreographed some of the most remarkable stunt scenes ever committed to film. Hanging Tom Cruise from the towering Burj Khalifa isn't the half of it. Much thought has gone into revitalizing obligatory scenes like car chases, with tense, witty twists involving Dubai sandstorms and Mumbai gridlock.

The acting isn't deep, but Cruise regains some of his star luster as superspy Ethan Hunt. His battles unfold with brutal grace and cleverness. Simon Pegg operates an array of wacky gadgets, from antigravity underwear to a portable mirage projector that is the best iPad app ever. This film isn't concerned with creating an air of heart- attack urgency -- its opening set piece, a prison riot in Moscow, is scored to Dean Martin's breezy "Ain't That a Kick in the Head?" -- but for jovial escapism, it's right on target.

The movie opens Friday in limited release at Imax theaters. A full review will run Wednesday, on its wide release date. Read an interview with director Bird at