Reporter Giorgio D'Amato agrees to meet his friend Enrichetta at Edmondo Parisi's villa, but when he arrives the model has been stabbed to death with a pair of scissors. Her presence at the villa had been requested by the crippled and neurotic Parisi who had invented a device which allows him to photograph thoughts. The other guests are a strange bunch: there is Eleonora, Parisi's lesbian wife; Alberto, the omnipresent butler and Lucia, the uninhibited housekeeper. The only normal person seems to be young Sara, Edmondo's niece, who enlists D'Amato to find the murderer. Soon the mysterious hand strikes again and this time it's Lucia's turn...