Mr & Mrs Smith opens with John and Jane visiting a marriage counsellor. They look like the perfect couple. He's Brad Pitt and she's Angelina Jolie. What could possibly be wrong with their relationship? The answer comes quickly, though nobody realises it at the time. Invited to look back on how they met, they recall the occasion as a mutual rescue operation that takes place in a hotel lobby in Bogota, Colombia, in the middle of a war zone. Their romance, born of the adrenaline-rush of a battleground, has lost its zing. To reignite the flame, they need a good skirmish. Both have it in them - they're assassins, after all - but their relationship has been wasting away behind the suburban facade of their dream home.

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Everything in this smart film is really something else. Both John and Jane think they're in charge of their realm, but neither is. His backyard shed is a front for the armoury required of a hitman; she hides her weapons in a secret drawer underneath the oven. But there are also forces at work that neither knows about, to do with each other and with the agencies whose interests they serve, and their only hope for survival is to rediscover each other.

Kinberg's knowing script provides the film with a solid, three-act structure as well as an engaging stream of doubles entendres. And even if they're not Grant or Hepburn, Pitt and Jolie bring plenty of spark to their performances. But while it's certainly fun to watch, what Mr & Mrs Smith lacks is passion. As a romantic comedy, it needs to make the fate of its lovers matter. But in the end you simply don't care enough about what happens to John and Jane.