Dickey is a gruff American gangster who shoves his broken-down car along a causeway while a rising sea closes in around him and his oddball companion, Albie, who lies inside wounded from a botched robbery. Cut off by the encroaching waters, they make for the only path to the remote tidal island of Lindisfarne in Northumberland, where a dark castle sits atop a hill and an intensely nervous, effeminate Englishman named George lives with his French second wife, Teresa, a young and impulsive woman.
Inside the fortress, Donald Pleasence conveys George’s deep seethe of nerves and theatrical vanity, while Françoise Dorléac embodies Teresa—a lure of youth and heat who flirts with danger as easily as she moves through rooms full of ostentation. The moment Dickey breaks into the castle, he seizes control of the place, calls his underworld boss, Katelbach, to arrange a pickup, and cuts the phone lines, turning the home into a hostage arena as he waits for the next day’s arrival.
As Albie bleeds out, Dickey forces Teresa and George to dig a grave for him and then presides over a grim wake, the two adults sharing cheap liquor on the beach while Teresa swims nude, a provocative splash against the castle’s grim atmosphere. The following morning, a car pulls up to the castle—this time not Katelbach, but a group of George’s loud, intrusive friends who have arrived unannounced. Dickey pretends to be a servant, while Teresa casts longing glances at one guest, Cecil, and the dinner unfolds with uneasy social comedy punctuated by fear.
A startling disruption comes when the young son of another guest finds Cecil’s shotgun and starts waving it at the terrified crowd, firing and blasting a stained-glass window. The weapon is wrestled away and stored in a hallway, heightening the sense that anything can explode into violence at any moment. Tensions simmer as Dickey reconnects the phone and discovers that Katelbach will not be sending help. With the plan crushed, he attempts to claim George’s car and drive to the mainland, but George refuses to yield.
What follows is a violent struggle: Teresa discreetly hands Dickey’s pistol to George, who then shoots the gangster multiple times. Dickey, too weak to press his own Tommy gun, collapses and fires the weapon at George’s car, setting it ablaze in a fiery explosion. Fearing arrest and retribution from Katelbach’s network, Teresa begs to flee, while George stands in a state of shock, not fully able to move.
As the castle empties and dawn breaks, Teresa and Cecil drive off into the night, leaving George alone with the chaos he has created. He rages through his art studio, then races to the beach, collapsing on a rock in a fetal pose. The morning tide swallows the shore as he sobs, calling out the name of his first wife, his voice thinning against the insistence of the rising sea and the relentless morning light. The island’s isolation closes in, leaving a stark portrait of a man undone by fear, memory, and the sudden, violent intrusion of outside forces.
