Wade Hildreth is sent to New York from London to receive a diamond necklace for Lady Gwendolyn from the jeweler Arabin. A gang of crooks led by Pete Fielding, known as "The Shadow," plans to keep Hildreth from going to Arabin's until they have robbed the store. Actress Morn Light, whom the Shadow loves, agrees to entice Hildreth to her apartment to be imprisoned. When she warns Hildreth because she wants to avenge her father's death, which was caused by the Shadow, the Shadow overhears and captures them both. With large numbers of shoppers in the store, the gang takes the necklace, other valuables, and the customers' possessions. Discredited Detective Tyron follows the gang's getaway boat and arrives with the Marines in time to stop the Shadow, against whom his gang is mutinying, from attacking Morn Light. The gang is captured, the Shadow jumps overboard, and Hildreth returns to England with the necklace and Morn Light, now his bride.