Prudence and Bélisaire Beresford have decided to take things easy. But when a rich Russian heiress disappears, Prudence can't resist and Bélisaire is forced onto the adventure. Their investigation will put them on the trail of a mysterious scientist who holds the secret to eternal youth...
Catherine Frot
as Prudence Beresford
André Dussollier
as Bélisaire Beresford
Nicolas Marié
as Doctor Nicolas Roscoff
Agathe de La Boulaye
as Doctor Matarazzi
Linh-Dan Pham
as Marie Van Dinh
Éric Naggar
as Doctor Jünger
Bernard Verley
as The General
Hervé Pierre
as The family doctor
Sarah Biasini
as Marie-Christine
François Bettens
as Rudi
Julos Beaucarne
as Prudence's father
Alexandre Lafaurie
as Hector
