A Reno singer witnesses a mob murder and the cops stash her in a nunnery to protect her from the mob's hitmen. The mother superior does not trust her, and takes steps to limit her influence on the other nuns. Eventually the singer rescues the failing choir and begins helping with community projects, which gets her an interview on TV—and identification by the mob.
Based on the 1930's comic strip, puts the hero up against his arch enemy, Shiwan Khan, who plans to take over the world by holding a city to ransom using an atom bomb. Using his powers of invisibility and "The power to cloud men's minds", the Shadow comes blazing to the city's rescue with explosive results.