A mysterious murderer known as "The Creeper" stalks a college town, killing first Professor Cushman and then socialite Joan Bemis. Hiding from the police, The Creeper, a frighteningly deformed man, takes temporary refuge in the apartment of Helen Day, a blind piano teacher. Because Helen shows no fear of The Creeper and treats him kindly, he spares her life. Later, Jimmy, a grocer's clerk, delivers groceries to the dockside room where The Creeper lives. Hoping to earn the reward for the killer's capture, Jimmy spies on him and is killed when The Creeper discovers him. When Jimmy fails to return, the police investigate and find a photograph of three college friends. The police then visit Clifford Scott, one of the two men in the photograph, and his wife Virginia, the third person in the snapshot. Clifford identifies the other man as Hal Moffat and tells his story: In college, Clifford and Hal are both in love with Virginia Rogers. Clifford tutors Hal, a football star, and one day, gives Hal a series of incorrect test answers so that he will not be able to keep a date with Virginia. In order to further torment Hal, Clifford walks Virginia by the laboratory, where Professor Cushman has given Hal an extra assignment, and the furious Hal drops a test tube and is badly burned in the ensuing explosion. Afterward, Hal disappears from the hospital. Convinced that Hal is The Creeper, the police warn Clifford and Virginia that they may be in danger and post a guard outside their house. When The Creeper again visits Helen, he learns that an expensive operation might restore her sight. He then evades the police guard outside the Scott's house and demands that Virginia give him her jewels. After Clifford pulls a gun on The Creeper, the two men struggle. Although he is slightly wounded, The Creeper strangles Clifford to death. The Creeper then returns to Helen's apartment and gives her the jewels to finance her operation. When Helen tries to sell the jewels, however, the police are notified, and horrified to learn that her friend is a murderer, she helps the police capture him. Later, the police arrange for Helen to have the operation.