Facing a tight deadline on a computer security contract, Aimée responds to a telephone call from a stranger that leads her to an abandoned infant in a courtyard on the Ile Saint-Louis. She brings the baby home with her, calls her Stella, and awaits contact from the mother. But days pass, and no one reclaims the infant. Meanwhile, a group of environmental protestors is trying to stop the government from entering into a contract with an oil company notorious for pollution. As Aimée attempts to identify the baby's mother, two murders and an abortive bombing involving the protestors lead her-and little Stella-into danger. On the run in the sewers beneath the Seine, Aimée finally finds the woman she has been looking for, only to discover that the man she has fallen in love with is not who she thought he was.