Tom Penderel, an American car salesman in London, heads to a windswept Dartmoor mansion to deliver a car to his eccentric roommate Casper Femm. A ferocious storm rages outside, a statue crashes to the ground, and the car is damaged in the chaos. Inside the dim corridors, Tom discovers that Casper Femm is dead, setting a grim tone for what is to come within the decaying estate.
A fragile agreement forms as Tom is asked to stay with Casper’s scattered family. The group includes Casper’s twin brother Jasper Femm, his cousins—the demure Cecily Femm and the alluring Morgana Morgana Femm—and their uncle Potiphar Potiphar Femm, who has been busy building an ark in anticipation of another great flood. The house itself feels like a wound of wood and stone, its creaks echoing the old loyalties and rivalries that lie just beneath the surface as night begins to fall.
Each relative is bound to return to the mansion before midnight every evening, or else forfeit his share of the family fortune. The constraint twists the atmosphere into a pressure chamber where fear and suspicion take root. Over the hours, a death toll begins to rise. Agatha Femm, Casper’s mother, is found dead with knitting needles lodged in her neck, marking the first hour of dread. The next victim is Jasper Femm, followed by Roderick Femm, the stern head of the family, each disappearance tightening the grip of mystery around the remaining survivors.
Tom quickly realizes the killer is a woman, and his suspicions briefly settle on Morgana. Yet the truth begins to tilt toward Cecily, who is revealed to be the actual culprit just before she confesses, explaining that her motive was a greedy hunger for the entire estate. Cecily flees the house, and Tom pieces together the perilous puzzle, understanding that time itself is the weapon at play.
With the clock ticking, Tom uncovers time bombs hidden within the clocks scattered throughout the mansion. He races to defuse each device, the danger mounting with every passing moment. In a final burst of nerve and ingenuity, he hurls the last bomb out of a window, where it explodes at Cecily’s feet and ends the immediate threat. The storm rages on outside as the remaining relatives confront the aftermath, leaving a chilling reminder of greed, secrecy, and the fragility of family ties in a night where every hour brought a new horror.
