Don Gallico (Vincent Price) is a magician, master of disguise, and inventor of Magic (illusion) in the late 1800s aspiring to become a star magician under the stage name Gallico the Great. Disguised as The Great Rinaldi, a headlining rival magician, Mr. Gallico performs a number of magic tricks successfully, building up to the reveal of his latest invention, the buzz-saw, an illusion that "severs" the head of the magician's assistant Karen Lee (Mary Murphy (actress)). Before Mr. Gallico can perform the buzz-saw illusion, the curtains come down to stop the performance. Businessman Ross Ormond (Donald Randolph) and his lawyer serve Mr. Gallico a cease and desist order against the performance of the buzz-saw trick much to the anger of Mr. Gallico. Ms. Lee's boyfriend, police detective Lt. Alan Bruce (Patrick O'Neal (actor)), is asked by her to intervene in the dispute between Mr. Gallico and Mr. Ormond. Mr. Gallico informs the detective that he signed a contract with Mr. Ormond's Illusions, Inc., a magician's trick provider, to invent new tricks. Mr. Ormond claims to own all work created by Mr. Gallico, not just the tricks produced for Illusions, Inc., Mr. Gallico's understanding.