Ms. Diaz is June Havens, a collection of alternately appealing and exasperating traits thrown together to satisfy market research data suggesting that audiences go for

women who are tough but not aggressive, flaky but not nuts, sexy but not actually having sex, and willing to fall for a certain kind of guy without entirely losing their heads. That certain kind of guy — “I’m that guy,” is indeed one of his more memorable lines — would be, in this instance, Mr. Cruise, who tries to walk the dental-floss-thin line between good-humoured winking and outright self-parody.

He plays Roy Miller (perhaps not his real name), a C.I.A. super-assassin who collides with Ms. Diaz’s character at the Wichita airport. She is going home to Boston for her sister’s wedding, while Roy is either trying to steal or trying to protect a powerful and secret energy gizmo that will eventually allow the filmmakers to introduce Paul Dano as the nerdy sidekick. Mr. Dano is especially necessary because the romantic chemistry between the principals — not unpromising in theory — sputters out like the initial blind-date spark on an early episode of a matchmaking reality show.

Meanwhile, Peter Sarsgaard, equipped with a superfluous accent to show what a serious actor he is despite the numskullery surrounding him, plays the heavy, Roy’s intra-agency rival, with Viola Davis as their boss. Not a bad cast, you will have noticed. But alas, as they ricochet across the globe, from a South Pacific island to the streets of Seville, they all seem to run out of things to do. Yes, there is a glowering arms dealer (Jordi Mollà) and his thuggish minions. Yes, there are trains and choppers, knives and guns, dead bodies and stolen kisses and all the other traditional 007 accoutrements, updated ever so slightly to conform to present-day sexual mores, geopolitical confusions and technological fantasies.