Star quality can cover a lot of plot holes, even the craters that trip up Knight and Day. Luckily, director James Mangold (Walk the Line, 3:10 to Yuma) keeps his appealingly athletic stars, Tom Cruise and Cameron Diaz, so avidly on the go you'll probably forgive the plot's resemblance to Killers, the Ashton Kutcher-Katherine Heigl caper now stinking up a theater near you.
The X factor in propulsive entertainment like Knight and Day is whether the stars can get you to go with the flow. Cruise really works at it. After two serious roles in Valkyrie and Lions for Lambs, he seems eager to raise hell again. Knight and Day plays like another chapter in Mission: Impossible and a TV game show called Survivor: Wichita.
It's at the Wichita airport where Cruise's Roy Miller, a secret agent who may have gone rogue, meets Diaz's June Havens, a Boston babe who loves carburetors but can't find a way to make her own life combust. Enter Roy, who finds time to hit on June even as the passengers and the pilots on their flight end up riddled with bullets. It's up to Roy to land the plane in a cornfield. It's up to June to decide whether to follow Roy on life-threatening adventures in New York, the Alps, Austria, Spain, the Caribbean and Cape Horn.
Is her decision really ever in doubt? Not in the Hollywood universe where Knight and Day was birthed. Mangold and co-writer Patrick O'Neill reference romantic-comedy twisters such as Hitchcock's The 39 Steps, Stanley Donen's Charade and Doug Liman's Mr. and Mrs. Smith. And the plot throws curves involving Roy's attempts to keep geek inventor Simon Feck (Paul Dano) – he's come up with a limitless energy resource – out of the hands of the CIA director (Viola Davis), an agency boss (Peter Sarsgaard) and a weapons dealer (Jordi Mollà).
You can't discount the kick of watching an overqualified cast go slumming for the pure adrenaline thrill of it. But Knight and Day rises or falls on how you feel about the body-and-soul chemistry between Cruise and Diaz, who first teamed in 2001's Vanilla Sky. It strikes me that their teasing and one-upmanship are more brother and sister at play than lovers in heat. Cruise and Diaz are in it for the action rush. You appreciate how hard they knock themselves out, but where's the sizzle?