Benjamin Malaussène and family are far from happy when his fortune teller younger sister Thérèse marries the aristocratic Count Marie-Colbert de Roberval at a televised wedding - a ceremony from which Marie-Colbert has unceremoniously banned the madcap Malaussène clan. Two days later, Thérèse turns up in Paris's Belleville quarter back early from their honeymoon, only to narrowly escape death as her fairground caravan is mysteriously torched to the ground.
When that same day his sister Thérèse's husband is found dead at the foot of his luxury apartment's stairwell, Benjamin Malaussène, professional scapegoat, packs his bags ready for the police to haul him off.
Only it's Thérèse the police arrest when she refuses to disclose her whereabouts the night of her husband's murder. Without her alibi - which might have something to do with her sudden pregnancy - it's over to Benjamin to save the day. Family and friends join forces to leave no corner of Paris unturned in their search for the true culprit.