Branded as criminally insane and incarcerated for a murder he did not commit, Speight escapes from the asylum, determined to clear his name. He befriends private detective Hugo Bishop who, convinced that the wrong man has been convicted, agrees to help find the real killer. They begin their search for the murderer closest to home where both Thelma Speight and her employer Maurice Jerrard were visibly distressed by the news of her husband's jailbreak. More than Speight's 'insanity' fuels their worries.

• Hammer Film Productions
• Paul Henreid
• Lois Maxwell
• Kieron Moore
• Hugh Sinclair
• Lloyd Lamble
• Anthony Forwood
• Bill Travers
• Mary Laura Wood