In Baltimore, two wax museum proprietors who double as amateur sleuths—Anthony Draco, [Cesare Danova], and Harold Blount, [Wilfrid Hyde-White]—find themselves drawn into a brutal case when they assist the police in pursuing Jason Cravette, [Patrick O'Neal], an unstable killer who murders a woman and then pretends to marry her. The crime shakes the city, and the pair quickly become entangled in a web of danger as Cravette is captured, tried, and convicted, only to escape during transport by severing his own hand. With a hook in place of his missing limb, he flees to New Orleans, presumed dead by the authorities, and hatches a plan for revenge against those he believes betrayed him.
Under a new identity, Cravette returns to Baltimore to settle the score. He abducts Marie Champlain, [Laura Devon], a prostitute whom he transforms into a refined companion, and brings her back to the city. Cravette uses Marie to lure the judge who condemned him, intent on murdering him in cold blood. After the judge is slain, the killer removes the judge’s arms and head, raising a chilling toast with champagne to celebrate the act.
Draco and Blount uncover the grisly crime scene and realize that the judge has been murdered, with only a report of a mysterious blonde clueing them in. A friend of the late judge eventually reveals his past weakness for women and the name “Marie,” sending the detectives on a deeper chase. Following Marie to her home, Draco visits her under the pretense of requesting a pose for a wax model, hoping to use her likeness in a larger, sinister project. Unbeknownst to him, Cravette urges Marie to cooperate, as she becomes embroiled in the conspiracy and its deadly twists.
While Draco is occupied with Marie, Cravette abducts Dr. Cobb, [Richard O'Brien], who had testified against him, murders him, and dispatches his severed hands to the police along with a cryptic note. Draco and Blount quickly deduce that Cravette is delivering a body piece by piece, the limbs and head missing, a macabre trail the police must decipher. Marie finally reveals the full story of the man she met in New Orleans, confirming Cravette as the vengeful killer they’ve been tracking.
A citywide dragnet closes in, and Cravette seems to be captured by Police Sgt. Jim Albertson, [Wayne Rogers]. But the escaped mastermind turns the tables, killing the patrolman with a pistol hidden inside a fake hand that matches his hook, forcing the investigators to rethink their approach. Draco, Blount, and the police then set a trap inside the wax museum, where Cravette plans to finish his grisly “body.”
The climactic confrontation unfolds within the museum walls as Cravette infiltrates the building, slipping in through the roof and knocking out Draco’s allies one by one. He confronts Draco with a merciless demand for a head, and after a brutal struggle using antique weapons, Cravette is fatally impaled on his own wax figure—an eerie, fitting end to a killer who crime-scene ambitions literalized the body on display.
In the aftermath, a grim reminder lingers: Marie receives a relatively light sentence of two years, and Draco and Blount discover, with a shiver, that the female wax dummy in their iron maiden exhibit is not a prop but a real murder victim. The revelation compels them to alert the police, sealing the case with a chilling note about the true cost of vengeance.
