Aimée is faced with a tight deadline on a computer security contract when a telephone call from a stranger leads her to an abandoned infant. She brings the baby to her home and names her Stella. She expects the mother to reclaim the child, but days pass as Aimée tries in vain to discover her identity. Her partner, René, urges her to turn the baby over to the authorities, but for Aimée this is too close to her own abandonment by her mother.
The search brings her among ecological protesters and oil company tycoons, newspapermen and would-be actresses, as demonstrators near her home on the Ile Saint-Louis, in the heart of Paris, march against the pollution of the North Sea only to be dispersed by armed police.
Two murders and an abortive bombing keep Aimée running until, in the sewers beneath the Seine, she finds the woman she has been looking for, only to discover that the man she has just fallen for is a cold-hearted criminal.