At the corner of Ocean View and Arch Street, a disoriented man stumbles out of the fog and into the street, where he is almost run over by cab driver Patty Mitchell. The man is suffering from amnesia and the only clues to his identity are a hatband imbossed with the initials "RD" or "DR," two ticket stubs from the Imperial Theater and a matchbook from the Blue Room at the Regency Hotel. Patty drives the man to a police station for help, but when they see a newspaper story reporting the murder of producer Robert Dilling on Ocean View by a man wearing a pin-striped suit and fitting the man's description, Patty decides to help her amnesiac passenger and drives him to a tailor, where he buys a new suit to hide his identity. At the tailor, they hear a radio bulletin announcing that Dilling's chauffeur, Dave Rennick, is suspected of the murder. Patty urges her passenger to leave town, but he insists upon going to Rennick's apartment to investigate. As they search the deserted apartment, Inspector Bill Brenner and reporter Haley arrive and begin questioning them. Patty states that they are newlyweds named Mr. and Mrs. Clarence Smith, and were innocently enjoying their honeymoon until "Clarence," a reporter, read of Dilling's death and saw a potential story. Believing that "Clarence" could be Rennick, Brenner invites him to the Dilling house, where Dilling's butler Judson denies that "Clarence" is the chauffeur. A search of Dilling's study reveals that the producer has been cheating authors of their play royalties. The man also discovers a manuscript entitled Two O'Clock Courage by Lawrence Tenny. When headquarters calls with the news that the tailor identified the murder suspect as one of his customers who was dressed in a pin-striped suit, Brenner arrests Judson, who is attired in a suit of that pattern. From the Dilling house, Patty and her passenger decide to visit the Blue Room at the Regency Hotel for more leads. At the club, the man is warmly embraced by Helen Carter, who calls him "Step" and tells him that she was afraid he might be involved in the Dilling case because he had argued with the producer in the theater lobby on the night of the murder. The man is also greeted by Mark Evans, the author of the play that Dilling was producing. Their meeting is interrupted when Evans becomes embroiled in a fight with actor Steve Maitland. After Helen leaves, the man visits Evans, who explains that Maitland attacked him because he tried to prevent the actor from appearing in his play. The man cleverly learns from Evans that his real name is Ted Allison, that they both attended college with Lawrence Tenny and that Tenny committed suicide. After Ted leaves Evans' apartment, he and Patty discover that a Ted Allison is registered at the Regency Hotel, so Ted returns to his room. Meanwhile, Brenner has arrested Rennick, who informs the inspector that he heard Maitland threaten Dilling. Brenner, accompanied by Rennick and Haley, visits Maitland, who admits to threatening the producer because he was annoying actress Barbara Borden, with whom he is in love. When Barbara tells Brenner that Dilling was upset about a conversation he had with Ted Allison, a guest at the Regency Hotel, Haley rushes to Ted's hotel room, where Ted has just found a note from Tenny's mother authorizing him to represent her son's play. Haley tries to restrain Ted, but he escapes and returns to the Billing house to retrieve the copy of Two O'Clock Courage . Just as Ted finds the play, a shot rings out, grazing his head and knocking him unconscious. In a semi-conscious state, Ted remembers accusing Dilling of stealing Tenny's play. Immediately after, Dilling was killed and Ted was struck on the head by his murderer. When Ted regains consciousness, he is arrested and taken to headquarters where he informs Brenner that Evans stole Tenny's play and that Dilling was blackmailing him because of it. Brenner then takes Ted to Evans' apartment, where Ted accuses the playwright of shooting Dilling when the producer interrupted his search for the last copy of the play. Evans confesses to the crime and goes into the next room to fetch his coat. Just then, a gunshot rings out and the police find Evans' dead body. While they fan out into the corridor, another gunshot draws their fire. Once the firing stops, they burst into the room and find the mortally wounded Barbara Borden, who admits to killing Dilling because he was blackmailing her over some old love letters and to killing Evans because he knew the truth. With the murders solved and his name restored, Ted marries Patty.