On a snowy morning, Kip Walton is released from Wormwood Scrubs Prison and makes his way to visit the grave of his wife, who died while he was inside. Back home, he begins to lay out a plan for a bank robbery inspired by a dying co-prisoner’s idea, hoping to turn his fortunes around. The scheme involves breaking into a basement bank vault through the cellar of a bombed house and linking to an old interconnecting air-raid shelter, a route that promises secrecy and risk in equal measure.
A gang is assembled by Steve Bannerman, Kip's young brother-in-law, whose talent for planning has earned him leadership despite never having pulled off a heist before. Kip collapses from a weak heart, leaving Steve to shoulder the burden and press forward with the plan. Steve has masterminded crimes in the past, but this is the moment he must translate theory into dangerous action, guiding the others through the methodical steps needed to reach the money.
The crew enters the basement of the empty building next to the bank, using a trap door and tearing through the wall that separates the two properties. Their audacious entrance leads them to a startling discovery: a large unexploded bomb from the Second World War sits in the space they’ve carved out, a grim reminder of the city’sRecent scars. A squeaking rat draws attention, and when Steve tries to shoo it away with a brick, the impact reverberates against the bomb’s casing, a moment that heightens the tension for everyone involved.
Undeterred, the gang plants explosives in the rear wall of the bank vault and proceeds to break through. Soon after, Steve detects the bomb’s ticking but decides to keep the sound to himself, a choice that foreshadows the peril closing in on them. Kip, meanwhile, returns home restless and impatient, with no one to keep him in check, and he arrives to see how the operation is unfolding. As the ticking grows louder, the men instinctively flee to minimize risk, yet a concrete lintel collapses onto Steve, injuring him and delaying the escape.
One member of the group forewarns his girlfriend in a nearby house, who promptly alerts the authorities, shifting the danger from a private plan to a public emergency. In a last, desperate bid to escape poverty, Kip Walton stays behind to retrieve the sacks of money, but his attempt to shift the beam that traps Steve triggers a fatal heart attack. As Steve crawls toward the trap door, he stumbles on loose bricks and collapses, exhausted. The ticking bomb, now uncontainable, explodes, sealing a grim fate for the would-be robbers and setting off a chain of consequences that reverberates through their lives.
