On a stormy night, elderly Ella Venable (Catherine Lacey) reads aloud a passage from Poe's "The Raven" before a man sneaks up behind her and clubs her over the head. Her body is wrapped up and carried outside as the woman's cat Tabitha, who witnessed the crime, quickly rushes out the door. The victim turns out to be a very wealthy woman who has been trapped in a loveless 30-year marriage to Walter (André Morell), who made no qualms about marrying her for her money. We also learn that her killer, Andrew the butler (Andrew Crawford), as well as the maid, Clara (Freda Jackson) are also in on the murder and have been promised a healthy cut of the inheritance if they play along. Ella's body is buried in a shallow grave somewhere on the property. A few days after the murder, Walter contacts the police to let them know his wife has disappeared. He's also taken provisions to ensure he's left everything in the estate by forging a will. However, the actual will is hidden somewhere in the home and must be found and destroyed before anyone else can get their hands on it. Promptly following Ella's disappearance, several relatives arrive at the home. First up is Ella's beloved niece Elizabeth (Barbara Shelley), who seems to be the only person her dead aunt actually loved. Also coming in for a visit are Walter's brother Edgar (Richard Warner), his sleazy, skirt-chasing son Jacob (William Lucas) and Jacob's smarmy wife Louise (Vanda Godsell). Those three are also in on the murder and, just like the two servants, have been payed off to keep quiet and assist in locating the missing will as well as helping throw off the investigators.
So who's going to teach these greedy, murderous, thieving scumbags a lesson? Why Ella's beloved pet puss Tabitha, of course! She makes life a living hell for each of the conspirators; clawing, hissing and causing a general uneasiness and panic amongst them. They all want her captured and killed, which makes them look all the more suspicious to both Elizabeth and the investigators. Hey, it's just a cat, right? But this cat is no ordinary cat. It ignores plates of poisoned meat left around the house and when it's lured into a trap by the tempting treat of live mice, put in a sack and stands the chance of being dunked in the backyard swamp waters, it manages to escape and knock someone into a quicksand bog in the process. The kitty also finds ways to start killing them off one by one; knocking one down a flight of stairs, giving the weak-hearted one in the group a heart attack by rushing at his head and finding other methods of punishing the guilty. Tabitha has plenty of clever tricks up her, uh, paw.
Naturally, a film portraying a domesticated animal going about getting revenge for its slain owner by committing premeditated murder is going to be called far-fetched by some, but this is a horror film we're talking about. I don't see why such nonexistent creatures as vampires, zombies and unkillable slasher maniacs who get shot hundreds of times but keep on tickin' are tolerated but people have a hard time accepting a vengeance-minded domestic cat doing the same thing. Any film with fantasy content requires the suspension of disbelief, and this is no different. But the movie is very well done for what it is. The cast is excellent, it's well paced, the Gothic mansion setting is perfect for this kind of material, the cat itself is fun to watch and there's an interesting score from Mikis Theodorakis, which alternates between commanding to almost whimsical. There is also some clever distorted camera-work to represent the cat's point of view.
Even though the production company is listed as BHP (who according to IMDb only did two other films), it might as well be considered a Hammer Production. In fact, the director, the writer, the editor, the cinematographer, the production designer, the makeup artist and much of the cast frequently worked for Hammer. It was also filmed at Bray Studios. I don't know if the studio lent its resources out to an independent producer or what, but this definitely has that Hammer feel to it and will probably be appreciated by any fan of their usual films.