On, June 5, 1944 in the early morning hours before the opening of the invasion on D-Day, a commando team, consisting of two New Zealanders, Captain Ben Grogan (Craig Hall
) and Sergeant Joseph Tane (Karlos Drinkwater
), land on the one of the Channel Islands, which are occupied by the German Army. Their mission is to sabotage installations there to create a distraction from the actual landings at Normandy.
Using kayaks they land on the beach, navigate the land mines, then climb up to their target: a large artillery gun overlooking the English Channel. They are confused by the lack of German patrols on the island and puzzled by strange screams coming from the Germans main bunker.
They find the gun unguarded and wire it with explosives. While they are placing the charges a German soldier (Luke Hawker
) comes running out of the entrance of the underground bunker. Although he seems less concerned about running into the enemy than getting away from something in the bunker, the New Zealanders kill him, so he can't give away the mission.
Captain Grogan becomes curious as to the screams from the bunker as they appear to be coming from a woman. He makes a decision to go on an unauthorized rescue mission, leaving a reluctant Tane behind.
Tane eventually decides to follows Grogan into the bunker. Inside he finds the command center a scene of unbelievable carnage, with German soldiers bodies torn asunder and blood all over the walls. He also finds a book which seems to contain satanic spells in a foreign language.
Tane isn't alone in the command center. SS Colonel Klaus Meyer (Matthew Sunderland
) comes up behind Tane, kills him and retrieves the book, leaving Tane dead on the floor.
Grogan, unable to find the source of the screams, backtracks and finds the command center along with Tane's body. He is also attacked by Meyer. Meyer doesnt kill him though, but captures him, ties him up and tries to get information out of Grogan about the coming invasion. He finds a picture of Grogans dead wife, Helena, who was killed during the bombing of London and threatens to burn it to torture him.
They are interrupted again by the woman's screams. Grogan states he believes that the Germans captured a woman and used her for entertainment and then Meyer got greedy, wanted her to himself and killed the rest of the soldiers. Meyer laughs at this and tells Grogan that the woman did all the killing. He then tells Grogan he needs to feed it. Scooping some human entrails into a bucket, he leaves the room.
While Meyer is gone, Grogan is able to grab and conceal a small can opener behind his back. When the German returns, he seems more reasonable and tells Grogan that the woman he hears is actually a demonic creature.
German soldiers found the satanic book on the island. The island has a long history of witchery. Meyer, a specialist in the occult, was sent to the island to see if it had any value as a military weapon. He found a spell and successfully conjured up the demon, but it turned out that the creature was a shape-shifter that can appear as any woman a man might desire. The demon used this power to lure the soldiers close, kill them and eat them. Meyer tells Grogan he wants to defect to the Allies and needs Grogan to assist him in sending the creature back to hell, a job that requires two people.
Grogan thinks Meyer is crazy. While they are talking he uses the can opener to cut his bonds and attacks the German. There is struggle. Grogan gets Meyers pistol. Meyers runs off into the darkness of a bunker tunnel while Grogan shoots at him. Grogan finds blood on the floor and realizes that the German has been hit.
Grogan follows the woman's screams and finds a chamber that looks like it has been used for a satanic ritual with markings on the walls and floor lit with candles. Around the room are of the remains of dead soldiers and crouching in the corner is the figure of a woman (Gina Varela
). When she emerges from the shadows Grogan is shocked to find it appears to be his dead wife. She pleads for him to release her as she is chained to the wall by her foot.
Meyers, appears at the door holding a rifle. He warns Grogan that the woman is not his wife and shoots her in the head and she falls to the floor. Grogan, enraged, tries to shoot Meyers with pistol, but its out of rounds. Meyers chops off the leg of one of a corpse and tosses it the woman, who suddenly revives, stands up and shifts into a red-skinned female creature with horns and sharp teeth. It begins to gnaw on the leg.
Convinced that it isn't his dead wife, Grogan goes back to the command center with Meyers, who is bleeding from a stomach wound. He agrees to help Meyers dispel the demon and allow him defect to the Allies side. First, however, the bullet must be removed from Meyers if he is to heal enough to do the ritual. Grogan does this, but without morphine to ease the pain, the Nazi passes out.
While he is out, Grogan examines a leather sack the German wears around his neck. Inside he finds a piece of paper with strange writing. Examining the book he finds the paper is a page that has been torn out. He replaces the paper with another page from the book and puts the original in his own pocket.
When the German wakes up he is well enough to attempt the ritual. Meyers explains that the leather pouch contains a spell that protects the person carrying it from being attacked by the demon. He tells Grogan that he will need to wear it for the ritual. Grogan gives it back to him. They head up to the demon's chamber, but find the she-devil has made progress in tearing the chain from the wall. They are forced to secure the door to the room with a spell and head back to the command center. Knowing the demon will soon break through the door they prepare a protective circle using the spell book in the command center. Grogan is plagued with visions of Tane coming back to life and accusing him of cooperating with the Germans, but Meyers is able to show him that this is just an illusion sent by the demon.
When the demon arrives, Meyers starts the ritual while the demon paces outside the circle tempting Grogan by appearing as Helena. As the ritual reaches its climax, Grogan realizes that Meyers isn't trying to get rid of the demon, but put it under his complete power, by sacrificing a human life: Grogan's. The German comes at him with a knife, but Grogan avoids him and throws him outside of the protective circle. Meyer thinks he is okay until Grogan shows him he has switched the page in the pouch. The demon they proceeds to eat the Colonel's head.
Grogan, safe under the spell page he carries, chains the demon back up in the command center, telling her that German reinforcements will be arriving soon, so she will have plenty to eat. He has no fear that she will leave the island as Meyers has told him a demon of this type cannot cross running water. Grogan then departs.
In a final scene we see the first German soldier (Nick Dunbar
) as he arrives at the command center. He is puzzled by finding his beloved, Nicole (Jessica Grace Smith
), there. As he comes to embrace her the screen fades to black and we hear a man's screams.