Former jewel thief and reformed detective Michael Lanyard, Warren William the Lone Wolf, is driving to a party with his loyal butler Eric Blore Jamison. Halfway there, they encounter Eve Andrews, Marguerite Chapman who asks to be taken to the home of Gerald Mohr Harry Cooper. Cooper, a criminal in disguise, has a plan to loot the jewelry of three wealthy women: Mona Barrie Jane Merrick, Tala Birell Sonia Budenny, and Marguerite Chapman Eve Andrews. But before he can carry out his scheme, Cooper is killed by an unknown assailant, leaving the fate of the loot unclear and the motive murky.
The sudden murder puts Lanyard in the spotlight, and the police, led by Inspector Crane, Thurston Hall, quickly fix their suspicion on him. He escapes custody, only to be found later by Sidney Shaw, a magazine writer who strikes a deal with him: keep quiet in exchange for a sensational scoop. With the pressure of being hunted mounting, the Lone Wolf turns his attention to the crime scene itself, interrogating the women who were meant targets and searching for a clue that could clear his name. Despite his efforts, the trail goes cold, and Lanyard is recaptured by two criminals under the direction of Cooper’s right-hand man—Louis Jean Heydt Arthur.
Lanyard breaks free again and reunites with his steadfast ally Jamison, as well as Shaw, and the trio hatches a plan to shadow Arthur as he heads for the airport. Their surveillance leads them to a hotel where Arthur meets a teenage girl named Margaret Hayes Patricia Blake. The revelation hits hard when Shaw, unaware of Cooper’s death, learns of Blake’s connection to the case, and her distress becomes a flashpoint for the tension surrounding the investigation.
In the hotel room, a confrontation erupts. Lanyard, Jamison, and Shaw rush in just as Arthur tries to recover his footing after a fierce struggle, and the pursuit spills into a flurry of close-quarters action. Arthur manages to slip away again, but not before Blake injures herself in the commotion and is tended to by Shaw. As the truth begins to surface, Blake reveals her feelings for Cooper, a disclosure that provokes a sharp, angry reaction from Shaw. The Lone Wolf pieces together that Blake is married to Shaw, and that linkage points to a deeper, dangerous motive behind Cooper’s murder.
With the pattern emerging, the police arrive and arrest the jealous lover, exposing Shaw as the killer who pulled the strings behind the late Cooper’s crime spree. In the end, the Lone Wolf is cleared of suspicion, and the case closes with a sense of relief and the promise of quieter days ahead for Lanyard, his loyal Jamison, and the investigative circle that supported him. Throughout the twists and near-misses, the story threads together glamour, danger, and wits in a classic mystery that tests loyalty, perception, and the cost of trust.
