Dr. Anton Phibes, Vincent Price, a celebrated concert organist with doctorates in both music and theology, is believed to have been killed in a car crash in Switzerland in 1921, while racing home upon hearing of his beloved wife Victoria’s death during surgery. Phibes survived the crash, but was horribly scarred and left unable to speak. He remade his face with prosthetics and used his mastery of acoustics to regain his voice. Resurfacing secretly in London in 1925, Phibes vows revenge, convinced that his wife was a victim of her doctors’ incompetence. He sets elaborate schemes in motion, targeting the very men he holds responsible for Victoria’s fate, all while being aided by his beautiful and silent assistant Vulnavia, Virginia North.
Phibes draws his murderous ritual from the ancient text of the Ten Plagues of Egypt, wearing an amulet whose Hebrew letters correspond to each plague as he carries out his grim plan. The killings unfold with a chilling precision, and after three doctors have fallen, Inspector Trout, Peter Jeffrey from Scotland Yard, becomes aware that Phibes’s victims had all worked under the direction of Dr Vesalius Joseph Cotten. Vesalius explains that the deceased had been on his team when treating Victoria, and that four other doctors and one nurse also share that history. When Trout finds a torn amulet at the fourth doctor’s murder, he traces its meaning first to a jeweler and then to a rabbi, hoping to uncover Phibes’s motive. The clues lead the investigators to Phibes’s mausoleum at Highgate Cemetery, where they uncover a box of ashes in Phibes’s coffin and deduce that Victoria’s coffin lies empty and that the true fate of Phibes himself remains a mystery.
As the net tightens, the police struggle to stop Phibes from striking again, and the calculated killer escalates his plan by abducting Vesalius’s son Lem, Sean Bury. Phibes calls Vesalius, demanding that the surgeon come to his mansion on Maldene Square if he ever hopes to save Lem. Trout tries to intervene, but Vesalius overpowers the inspector and races to the enigmatic residence. Phibes reveals that Lem lies under anaesthesia, and a key has been implanted near the boy’s heart to unlock his restraints. The time limit is devastatingly short: six minutes—the same span Victoria endured on the operating table. If the key isn’t removed within that window, acid will be released from a container above Lem’s head and finish the boy’s life. Vesalius manages to extract the key, freeing Lem just in time, and avoids a deadly cascade of acid.
Meanwhile, Vulnavia surprises Trout and her associate as she attempts to sabotage Phibes’s macabre machinery; in a flash of treachery, she is drenched with acid and killed, a crushing blow to Phibes’s inner circle. With the boy safe for the moment, Phibes withdraws to the basement where he seals himself inside a stone sarcophagus beside the embalmed body of Victoria. He drains his blood and replaces it with embalming fluid, then settles into the tomb as the lid slides shut, a final act that seals his vengeance for eternity. The police arrive, searching for Phibes, but his presence remains a mystery as Trout and the others remember the “final curse”—darkness—just before the basement plunges into pitch black.
