The conceit is a decent idea for a thriller, if not a terribly original one, but Shapiro loses the rhythm with a plodding story and a pat ending we can see coming a mile away.

Monogamy is a tough little movie. And a good one.

There are certain filmmakers who should have their Cassavetes card revoked, and on the evidence of "Monogamy,'' Dana Adam Shapiro has joined their ranks.

Director Dana Adam Shapiro has turned out a fascinating exploration of what can happen when we make assumptions about the person we love and the relationships we're in, and how easily we can destroy ourselves in the process.