Wrongly accused of murdering his brother, Geoffrey Radcliffe (Vincent Price) is found guilty and sentenced to die. But when sympathetic Dr. Griffin (John Sutton) injects him with a serum that renders him invisible, Radcliffe is able to escape and search for the real culprit. With Inspector Sampson (Cecil Kellaway) of Scotland Yard hot on his trail, Radcliffe begins to suspect that a recent hire in his family's mining company might have the answers he seeks.