Prime

Rom-coms are so difficult. As well as being grazing grounds for TV stars (Jennifer Aniston, Sarah Jessica Parker), put out to grass after their series have imploded, they are also traps for decent actors (Hugh Grant, Ryan Reynolds), who graduated from charm school with honours.

Occasionally they surprise, when someone who doesn't belong there is there. It happens in Prime and the "someone" is Meryl Streep. She plays Lisa, a therapist, whose 23-year-old son David (Bryan Greenberg) starts dating Rafi (Uma Thurman), a 37-year-old still vulnerable divorcee, who happens to be a client.

What pulls the movie out of the morass of heated up yesterday's leftovers is the script (Ben Younger) and the performances. Once you get over the embarrassment-is-funny style of humour ("His penis is so beautiful, I want to knit it a hat"), there is a serious understory about the generation gap ("I have shirts older than you") and how to maintain a relationship once you have had sex "on every surface of my apartment".

The situation has potential, but remains a one-trick pony. Rafi gabbles on to Lisa about her fab sex life with David, when you and I know she's talking about Lisa's son. Once the post-orgasmic rush has calmed and the reality of living together with a 14-year age discrepancy "the wrong way" - toy boy rather than cradle snatcher - David starts growing up.

In addition to his immaturity, which seems exaggerated by Rafi, because he appears in every sense a decent guy, there is the religious question. Rafi is a lapsed Christian and David, who is Jewish, goes through the motions for his mom's sake because that side of the family is orthodox and would disapprove of any amorous association with a Gentile.

Streep is terrific, Thurman is aglow and Greenberg is a real find. They work so well together that suddenly rom-coms don't look so difficult after all. And then they blow it.

Someone, who should be taken out and force fed Doris Day/Rock Hudson movies, made the worst decision of their life and tagged on a "year later" epilogue, which neither makes sense, nor satisfactorily concludes anything. You are left baffled, asking, "What was that about?" In an attempt to neatly package a relationship that once thrived on its diversity, this reeks of phoney closure and is such a disappointment in a movie that, up until this point, had avoided sentimentality.

You walk away feeling like Chicken Little's dad when the sky didn't fall.