Directed by Mario Bava under the name John M. Old, this film — known as What! and Night Is the Phantom in the U.S. — was removed from Italian theaters due to its BDSM themes, with censors claiming “several sequences refer to degenerations and anomalies of sexual life.”
It was written by Ernesto Gastaldi (billed as Julian Berry), Ugo Guerra (Robert Hugo) and Luciano Martino (Martin Hardy), after Gastaldi was shown The Pit and the Pendulum.
Within an isolated castle, the prodigal son Kurt (Christopher Lee) has returned. He once pledged to marry Nevenka (Daliah Lavi, Some Girls Do), but had an affair with Tania, the daughter of their servant which ended in her suicide. He left in disgrace while his fiancee instead married Cristiano (Tony Kendall, who was in the Kommissar X movies), the younger son of the Menliff family.
Supposedly, Kurt is back to celebrate their marriage, but really he’s just here to take Nevenka to the beach where he whips her. And here’s the part that upset people. She loves it.
Kurt is soon killed by the same knife that his illicit lover used to take her own life. But then his ghost remains, ready to ruin the lives of everyone in the crumbling manor.
Lee had hoped to work with Bava on another movie, but their busy schedules kept them from ever working together again. Upon seeing A Bay of Blood, he was so upset by its gore that he left the theater.