German film-maker Sandra Nettelbeck gives us this coy and unendurable tale of a tastefully sexless May-to-December romance, adapted by Nettelbeck herself from a 2006 novel entitled La Douceur Assassine, or Sweetness Murders. The cloying sweetness of this film is pretty murderous.

Michael Caine is Mr Morgan, a lonely American widower in Paris, given to wry fantasy-ghost conversations in public parks with his amused late wife. One day on the bus, he bumps into Pauline (Clémence Poésy), a beautiful young dance teacher who finds the old grump utterly beguiling.

When Morgan's angry and baffled grownup children Miles (Justin Kirk) and Karen (Gillian Anderson) enter the picture, they look like they might just put some grit into this preposterous picture, but Karen vanishes and Miles is absorbed into the film's sugary embrace. It is difficult not to remember the 2006 film Venus, about Peter O'Toole's ageing actor obsessed with a teenage girl. That at least was candid about the realities of sex. This is mealy-mouthed and sentimental about sex and everything else.