The Beast in the Cellar is a 1971 British horror film written and directed by James Kelly and starring Beryl Reid and Flora Robson.

The authorities suspect a wild cat, but sisters Joyce and Ellie Ballantyne, who live in a house nearby, fear that the soldiers are actually being murdered by their brother Steven, who has been locked in their cellar for nearly 30 years.

After their parents died, Joyce, not wanting Steven to end up like his father, resolved to prevent him from being called up at the start of the Second World War.

After being physically abused by his soldier father, then incarcerated for three decades by his sisters, Steven has developed a hatred of uniformed army men and regressed to the level of a savage.

[3] Christopher Neame says the central idea was based on a true story about two sisters who did not want their brother to go to war, so locked him up in the cellar.

[citation needed] The film was acquired for North American distribution by The Cannon Group Inc., and released theatrically at drive-ins in Philadelphia, Pennsylvania on December 1, 1971; again it was paired with The Blood on Satan's Claw.

Unfortunately, the material which precedes this is stretched so far beyond its natural dramatic length that the atmosphere never manages to get much of a grip on the imagination, and some consistently ill-chosen music doesn't help.

Only the occasional line of dialogue ... conveys the precise nuance of the situation which the film milks so laboriously – that of the sweet old ladies struggling to live with their unspeakably nasty secret.

And in the context of their impassive gentility, the obligatory injections of sex (a girl having her knickers pulled down in the spinsters' barn) and gore (Ellie pushing a clawed eyeball back into its socket) seem all the more obtrusive.

[12] TV Guide awarded the film 1/4 stars, stating that "The potentially interesting premise is undone by an extremely chatty script.