The film is based on the stage play "Angel Island" by Bernadine (Bernie) Angus, with an Agatha Christie-like plot in which deaths occur, suspects abound and guilty secrets are revealed. "Fog Island" was originally released by Producers Releasing Corporation (PRC), which got its start in 1939 with "Hitler: Beast Of Berlin" – a bit of anti-Nazi propaganda offered at a time when other production companies were more hesitant to take a stand on the European crisis. In addition to low-budget thrillers such as "Fog Island," PRC was responsible for a number of Westerns including "The Lone Rider" movies which featured a character whose black mask is reminiscent of another "Lone" character audiences of the Forties would have known. Director Terry O. Morse (also listed as Terence Morse) directed several pictures for PRC and is also known for directing the first of the Godzilla movies: "Godzilla, King Of The Monsters" (1954).
Fans of PRC films may appreciate seeing Zucco play opposite Lionel Atwill, another actor who specialized in eye-popping villains for the Poverty Row production company. He had been on-track for a promising career in bigger-budget Hollywood films until his reputation was destroyed by scandal when he was convicted of perjury in a criminal trial a couple of years before his appearance in "Fog Island."