Eleanor Byrne, Valerie Hobson, and her husband Murray Byrne, James Donald, ride home from a tense train journey to Llanbach, Wales, where the war has left Byrne with a missing leg and a lingering bitterness. Their relationship is tested as they drift apart—she a stage actress, he a playwright who carries the memory of his injuries and a sharpened sense of grievance. The mood is quiet but charged, a domestic front stage set against a larger backdrop of escape and danger.
As night falls, a country road twists into danger: a police roadblock shuts down the way, and the couple are reminded that three ex-army men have escaped from Dartmoor Prison. Five minutes later the atmosphere of routine turns deadly when broken glass and a bent parapet signal trouble at a nearby bend. A dark figure tumbles into view, claiming there is another man in the car, and suddenly the Byrne home becomes a beacon for terror. They decide to help the injured man in the kitchen and phone for medical aid, hoping to contain the crisis rather than escalate it.
From the shadows, the convicts move with purpose. One man disappears and steals their car, while the first man fumbles back to the road to locate the third member of the trio. It becomes clear they hit another car—its chauffeur is dead and two frightened children lie hidden in the back seat. The criminals force their way into the Byrne house, and the children are locked away in one room with Mrs Potter, the housekeeper Joan Young. The Byrnes, meanwhile, are confined to another room, their irony punctuating the mounting tension as they realize how quickly their ordinary lives have collided with extraordinary danger.
On the following day, the Sunday newspaper breaks the news that the escaped convicts have also killed a policeman, intensifying the sense that no one is safe. The children, now witnesses to a violent intrusion, are surprisingly articulate and begin to correct the invaders’ grammar, a small, unsettling reminder of a world that still clings to order even amid chaos.
Mrs Potter uses a momentary distraction to give Mrs Byrne a chance to slip away through an upper window. Her escape is short-lived, as she is soon caught by Boke, the who leads the gang and speaks with a swagger born of years in prison and a past in Liverpool and Chicago, a backstory he reveals in a chilling aside. He wants control, and his cold pragmatism weighs heavily on the house as the intruders tighten their grip.
The situation grows increasingly dire for the Byrne family. The well-educated children—still parsing the chaos around them—bear witness to the psychological pressure on both sides of the door, while the confrontation between the criminals and the homeowners escalates. The tension shifts again when the injured boy in the house raises the stakes with a medical urgency that cannot be ignored, hinting at meningitis.
In a moment of danger, Boke’s impatience with the screaming ignites the room. He moves to shoot the boy, but Mr Byrne finds an unattended gun and steps forward to intervene. The safety catch remains on, and in a tense exchange, Boke points out the mistake—an oversight that gives Byrne the opening to act. With the safety off at last, Byrne shoots and kills Boke, ending one of the most dangerous threats to their fragile family unit.
The aftermath settles over the house as the criminals’ threat dissolves into memory, and the police—together with the now-unified Byrnes—begin to piece together what their shared ordeal has revealed about trust, control, and the thin line between civilization and peril.
