In Serious As Pleasure, Jane Birkin, Richard Leduc and Raymond Bussières are three happy-go-lucky swingers who live quite happily together in a romantic liaison. One day they decide to take a trip in their beat-up car, managing the whole affair in their own special, insouciant manner. They are followed by a suspicious policeman who thinks there's something fishy about this group. Look for a cameo appearance by Serge Gainsbourg and a brilliant original soundtrack composed by singer/songwriter Michel Berger.