Following a series of jewelry store robberies by an armed gang wearing cat masks, Interpol sends Marie Watteau to the scene of their latest raid: Rome. But tracking down the gang is the least of her problems. First, she must rein in the local carabinieri, headed by Major Livia de Angelis, whose resentment of Interpol's interference leads to a clash of wills. But is that the only reason for de Angelis's defiance, or is she following some private agenda? In chasing down the Purple Cats, Watteau soon finds she is merely scratching the surface of a multi-layered intrigue...