The Infidel (15)

And talking of faith, David Baddiel's debut screenplay pitches Judaism against Islam in a potentially incendiary face-off.

Omid Djalili plays Mahmud, a London family man and Muslim of no especial devoutness who, on the death of his mother, discovers that he was actually born to Jewish parents, then adopted.

His real name? Solly Shimshillewitz. Needing to mug up on the culture of Jewishness – not quite the same thing as Judaism – he throws himself on the mercy of Lenny (Richard Schiff) who, in another unlikely transplant, is a Jewish-American black cab driver: how to say "oy" with a shrug, how to dance like Topol, and so on. (The Talmud doesn't get a look-in). The first 20 minutes or so hit a confident stride and raise some laughs, including a good running gag on that irksome habit of scratching quotation marks in the air, while Djalili and Schiff work up a droll double-act in the search for Mahmud's new identity. But it doesn't last, undone less by the weak subplot about his son's prospective father-in-law (a visiting radical Muslim) than a drastic collapse in quality control: the sly humour at the outset dwindles into scattergun farce, dubious fantasy sequences and can't-we-just-get-along mawkishness.

Ambitious to try a comic variation on Philip Roth's great The Human Stain, but it also requires subtlety, discipline and tougher editing.