Duris and Peilhas are at loggerheads: she wants a child, he doesn't. During a Millennium eve party, he climbs through a skylight and finds himself in 2070, in a climate-changed Paris under 20 feet of sand. Furthermore he's accosted by a strange old gent (Belmondo) claiming to be his future-conditional son, who's never going to get himself born unless Duris abandons his birth control policy. A gang of agitated descendants join in the clamour, pursuing 'granddad' back to 31 December 1999, where the party is just warming up. This is the small scale, intimist comedy of When the Cat's Away... grafted on to big budget whimsy. Sometimes amusing, sometimes silly, the movie takes great care to be pro-life without being Pro-Life, as its series of climactic climaxes (hetero and homo) make clear.