A young woman is found dead, her face half shot off and only a tattoo of a sphinx moth giving any hint of her identity. The tattoo links her to three similarly marked girls--all victims of the underworld sex trade--who have been rescued from the Mafia night-club circuit by a prominent Catholic charity. When Inspector Salvo Montalbano delves into the case, his inquiries elicit an outcry from the Church--and soon the three other girls are all missing.