The Devil’s Rock

On June 5, 1944, Captain Ben Grogan and Sergeant Joseph Tane land on a German-occupied Channel Island using kayaks. Their mission is to sabotage German installations and create a distraction for the Normandy invasion. They navigate land mines and approach a large artillery gun overlooking the English Channel.

The commandos discover the artillery gun is unguarded, and wire it with explosives. While working, they hear strange screams from a nearby bunker, which confuses them given the lack of German patrols on the island. Captain Grogan becomes curious about the source of the screams.

Grogan decides to investigate the screams further, leaving Tane behind. He ventures into the bunker alone, and finds it ravaged with blood and torn bodies, indicating a horrific event occurred there. He also finds a mysterious book with satanic spells.

Tane follows Grogan into the bunker and is killed by SS Colonel Klaus Meyer, who retrieves the satanic book. Meyer appears to be involved in occult practices and seems more interested in the supernatural horror than the military operation. He leaves, taking the book with him.

Grogan is captured by Meyer and tied up. Meyer tries to extract information about the invasion while revealing his fascination with the island's witchery and the demonic creature. Meyer shows Grogan a picture of his late wife Helena, killed in London, and threatens to burn her photo.

Meyer explains that the satanic book conjured a shape-shifting demon that appears as any woman one desires. The demon has been killing soldiers to feed on them. Meyer wants to defect to the Allies and needs Grogan's help to send the demon back to hell.

Grogan uses a can opener to free himself and fights Meyer, who flees into a tunnel. Grogan discovers the demon's chamber, which shows signs of satanic ritual, and finds the woman chained there, who appears to be his wife. Meyer reappears and shoots her, revealing she is a demonic creature.

The chained woman revives after being shot and transforms into a horned, sharp-toothed demon. Grogan is enraged and tries to shoot Meyer, but the German wounds him and the demon devours Meyer's head. Grogan then prepares to contain the demon once again.

Grogan and Meyer attempt a ritual from the spell book to banish the demon. Meyer wears a protective spell pouch, but it is later stolen and replaced with a different page. As the demon arrives, Meyer begins the ritual, but Grogan discovers that Meyer intends to sacrifice him to gain the demon's power.

Grogan prevents Meyer from sacrificing him and switches the spell page, causing the demon to devour Meyer instead. Grogan then chains the demon back in the command center, confident that the island's boundaries prevent it from leaving. He warns her that German reinforcements will arrive soon.

The film closes with a returning German soldier arriving at the command center and finding his lover, Nicole, seemingly alive. As he embraces her, the scene fades to black and we hear screams, implying the horror persists on the island despite the events.