A silly conspiracy thriller, The Forgotten starts strongly with an attention-grabbing premise: grieving mother Julianne Moore is told by her psychiatrist that her dead son only ever existed in her head. Refusing to believe this, she goes on the run, urging an alcoholic neighbour (Dominic West) to remember his child while government agents try to track them down. The question is whether she is delusional or devoted. The answer, when it arrives, is disappointing and daft.

From Short Cuts to Magnolia, Moore has made a monopoly of playing on-the-edge women dismissed as hysterical. She's good again here; it's just a shame the tears, emotion and anger are wasted on a character stuck in an over serious, somewhat self-important episode of The X-Files (a show which, at least in its early days, had a sly, dry sense of humour).

"IT MAY MAKE YOU THROW POPCORN AT THE SCREEN"

Like an elaborate, engrossing joke whose punch-line is limp-wristed, the filmmakers' deliver a strong set-up and then run out of ideas. "The goddamn truth won't fit in your brain," yells a desperate agent. Sadly, the "goddamn truth" would fit on the back of a postage stamp. 50 years ago the 'reveal' might have appeared daring or scary, playing off contemporary fears of nuclear contamination and communist invasion; now it may make you throw popcorn at the screen.

It's all the more frustrating given the quality cast; Edwards and Sinise are solid in supporting roles and the up-and-coming West is charismatic and engaging. There are also some decent shocks (an out-of-nowhere car crash is exceptional). But the superior jolts can't compensate for the cuckoo conclusion.