A psychotic small-time criminal realizes that the everyday robberies, rapes and murders he commits aren't profitable enough, so he figures to hit the big time by kidnapping the daughter of a rich man.
Engineer Quiller has become rich by selling his completely indestructible shop-window glass to jeweleries around the world. But this got him lots of enemies too: the insurance agencies, who've lost hundreds of customers, and the burglarers. When he temporarily looses his memory and voice in an accident, of all people, a family of thieves finds and cares for him - believing he's a pocket-picker. Things get complicated when he falls in love with his host Tilli.
Antonio Barozzi moves from Lago Maggiore to Rome to become an actor. He does not realize his agent and acting coach are only manipulating him to further their own careers.
