Jerry Barker finds a lost boy whose rich father is extorted into paying a ransom for his return but the boy accidentally dies and Jerry goes to prison.
While on vacation in Istanbul, mystery novelist Cornelius Leyden (Peter Lorre) is given the opportunity to view the body of the recently deceased criminal mastermind Dimitrios Makropoulos (Zachary Scott).
Helen, a speech-impaired caregiver, is implored by her bedridden mistress to leave her mansion filled with anti-social individuals when a series of murders occur in the neighbourhood.