Leo Grainger (George Zucco), a former investment broker recently released from prison, is living in seclusion on Fog Island with his stepdaughter Gail (Sharon Douglas). Gail has fled to the island, once a refuge for pirates, because Leo's release has prompted renewed newspaper interest in the story of his supposed investment swindle and Gail's mother Karma's violent death during his imprisonment.

Leo's former "associates" believe he has a hidden fortune somewhere on Fog Island, so Leo invites them all for the weekend, confident that the greedy group will not suspect he is setting a death trap.

When everyone arrives, Alec Ritchfield (Lionel Atwill), John Kavanaugh (Jerome Cowan), Sylvia Jordan (Veda Ann Borg), and Emiline Bronson (Jacqueline deWit), Kingsley's son Jeff (John Whitney), and Dr. Lake (Ian Keith), Leo's sinister ex-accountant, who served time with him. The atmosphere of mutual suspicion and the thick fog that covers the island promise a tense and hazardous weekend for everyone.

Jeff tries to make time with his indifferent ex-girlfriend, Gail. Leo gives party favors to his guests. A pen for Emiline Bronson. A small book of multiplication tables for John Kavanaugh. A toy skull for Sylvia Jordan. A chisel for Alec Richfield. A knife for Jeff Kingsley. And a key for Gail. Sylvia and John plot to steal the key, while Emiline discovers a note inside her gift, which directs her to look in a box on the mantlepiece.

Alec persuades Emiline to conduct a seánce around a large desk. During the seánce, Alec slips away and enters the house's secret passageway. The seánce ends abruptly when the desk starts to levitate. Lake accosts Allerton (George Lloyd), Leo's butler, and after identifying him as escaped convict Al Jenks, throws him out a window to the churning sea below.

Later, Alec sneaks down to retrieve Emiline's still unclaimed key but is interrupted by Leo. Alec stabs and kills Leo, and returns to the mantle just as Emilene finds the key and offers to show her where it fits in exchange for half of Leo's booty, then Alec leads Emiline into the passageway, and stabs her.

Meanwhile, upstairs, Jeff and Lake start to fight. Lake knocks out Jeff and flees. Sylvia and John meet up with Alec in the passageway. Using all the clues from their tokens, the three make their way to the cavernous cellar and, after being joined by Lake, locate Leo's treasure box, which they discover contains only a spiteful note. The cellar's entrance then closes and sea water begins seeping in through the floor.

Gail and Jeff, meanwhile, activate a trigger in the desk, which causes it to levitate and reveal a hidden drawer. Gail opens the drawer with Leo's key and finds her mother's jewels and a note, in which her mother advises her to forget about the past and move on with her life. After admitting to Jeff that she ran away because she feared that others suspected her of trying to steal Leo's fortune, Gail prepares to leave the island with Jeff. While readying to go, Jeff stumbles onto the passageway and discovers not only Leo's body but the drowned Alec, Sylvia, John and Lake as well. Without telling Gail the horrors he was witnessed, Jeff escorts Gail to the waiting launch.

A 1945 American Black & White mystery-suspense film directed by Terry O. Morse, produced by Leon Fromkess, screenplay by Pierre Gendron, based on Bernadine "Bernie" Angus' play "Angel Island" (1937), cinematography Ira H. Morgan, starring B-Movie horror film regulars Lionel Atwill and George Zucco, also with Jerome Cowan, Sharon Douglas, Veda Ann Borg, John Whitney, Jacqueline deWit, Ian Keith, and George Lloyd.

Based on the play, Angel Island (1937). Comedy-mystery. Written by Bernie Angus. Directed and produced by George Abbott. National Theatre: 20 Oct 1937- Nov 1937 (21 performances). Cast included: Joyce Arling, Carroll Ashburn, Nigel Blake, Clayton Collyer, Morgan Conway, Alma Dickson, Betty Field, Clyde Fillmore, Arlene Francis, Thomas Graham, David Hoffman, Louise Larabee, Doro Merande, Lea Penman, Maidel Turner, Edith Van Cleve, Eric Wollencott.

The sets were designed by the art director Paul Palmentola.

This almost forgotten film from the Producers Releasing Corporation (PRC) was best remembered for bringing together the screen's two "masters of menace," George Zucco and Lionel Atwill. For fans of low-budget Forties' movies, especially those which feature mystery, death and strange animals, human and otherwise, roaming the moors, two names stand high in the pantheon of actors who deliver the goods: George Zucco and Lionel Atwill. They were born within a year of each other in England, Zucco in 1886 and Atwill in 1885. Both had distinguished stage careers. Zucco left Britain for Hollywood in 1935. Atwill arrived in America in 1915.

A simple but entertaining, cheap, decent little thriller is an atmospheric '40's creeper, with gloomy and surprisingly rich-looking interiors. An early, low-budget spin on "Ten Little Indians." Worth a watch.