Several moments are pretty explicitly homages to A bout du souffle, but more than that, the film shares its predecessor's stylish, light-hearted existentialism.

Fred (Christophe Lambert) is a vague sort of criminal -- shortly before the start of the movie, trophy wife Helena (Isabelle Adjani) invited him to her birthday party after he helped her carry in some groceries, and he subsequently blew up the safe and stole a bunch of blackmail material; but it's never clear if he'd planned this from the start or just robbed the safe on anarchic impulse.

Now he's hiding out in the tunnels under the Paris metro, among a variety of subway workers, pickpockets, homeless people and street vendors. But he's less interested in his current predicament than he is in (a) starting a band (he's unable to sing himself, due to a childhood injury, but he longs to be the manager) and (b) scoring a date with the trophy wife, who comes down into the subway to look for him.