At the turn of the 20th century in the fictional village of Clagmoor Heath in Cornwall several locals are dying from what is deemed to be the "Black Death". Harry Spalding inherits his late brother's cottage and arrives with his new bride, Valerie . The inhabitants of the village keep clear of the newly arrived couple and only the publican, Tom Bailey, befriends them. Bailey explains that the hostility exhibited by the townspeople is the result of many mysterious deaths in the community. The sinister Dr. Franklyn, the owner of the nearby Well House, is the only resident in the vicinity of the cottage and he lives with his daughter Anna. The Doctor treats his daughter with cruel contempt and she is attended by a silent Malay servant. Hoping to learn something of the deaths, Harry invites the local eccentric, Mad Peter, home for dinner. After warning them that their lives are in danger, Mad Peter quickly departs only to return later that evening foaming at the mouth, with his face blackened and swollen. He dies within a few minutes. The Spaldings attempt to alert Dr. Franklyn, but Franklyn arrogantly states that Peter's death is not his concern, explaining that he is a Doctor of Divinity, not a surgeon. In an attempt to help Harry clear up the mystery, Tom Bailey illegally unearths Mad Peter's corpse and discovers a strange neck wound like a snake bite. Harry and Tom dig up the coffin of Harry's dead brother, Charles, and find that corpse also has those same strange marks. Realizing that they are threatened by something far worse than they had ever imagined, Harry is quick to answer an urgent message from the Well House. There he is bitten by a mysterious reptilian creature, but he still manages to return to his home and recover from the bite. Meanwhile, at the eerie abode, Valerie witnesses Dr. Franklyn's attempt to kill his own cursed daughter. She also witnesses a fierce struggle between the doctor and the deranged Malay servant. During the battle, a lantern is overturned and Dr. Franklyn is bitten by the venomous fangs of his reptilian daughter. Both the doctor and the reptile die in the fire and the Well House crumbles in flames, with Harry and Valerie fleeing for their lives.
The production was filmed back to back with The Plague of the Zombies, and used many of the same sets, including exterior shots in the grounds of Oakley Court near Bray, Berkshire. Pearce and Ripper appeared in both films. The cottage used in the film was located in Brentmoor Road, West End, Woking, Surrey. The heathland shots were of West End & Chobham Common. As documented in books on Hammer Film's history, actress Jacqueline Pearce disliked wearing the Reptile make-up as she suffered from claustrophobia. After this film she vowed never to wear "creature" make-up in her future acting projects. The film was released in some markets on a double feature with Rasputin, the Mad Monk. A novelization of the film was written by John Burke as part of his 1967 book The Second Hammer Horror Film Omnibus.
Critical reception
The Hammer Story: The Authorised History of Hammer Films called the film "classic sixties Hammer"; while Allmovie wrote, "there are some inconsistencies in Anthony Hinds' script, but the film is handsomely mounted and delivers its share of shocks" ; Time Out wrote, "it's slower and moodier than its companion-piece, but strikingly Conan Doyleish in its stately costume horrors. Jacqueline Pearce is terrific"; and British Horror Films said simply, "it's superb". The Monthly Film Bulletin wrote that it "has an unusually controlled dignity for a Hammer production; instead of the customary blood-lettings, we are invited to observe with nervous curiosity the slow self-destruction of a proud but superstitious man incapable of rescuing his daughter from the fate half-wished upon her by himself... Altogether, a film of quite some merit." Kevin Thomas of the Los Angeles Times panned the film, writing that "the script is too silly for all but the most uncritical."
