It's Double Danger for detective-story writer Robert Crane (Preston Foster) whenever he pursues his "secret life" as a suave jewel thief. Eluding police commissioner David Theron (Samuel S. Hinds) at every turn, Crane intends to snatch the famed Konjer diamonds from under the nose of jeweler Gordon Ainsley (Donald Meek). Things take a sinister turn when a humorless professional crook (Paul Guilfoyle) tries to cut himself in for a piece of the action. RKO Radio starlet Whitney Bourne delivers perhaps her best performance as giddy female thief Carolyn Morgan. Had Preston S. Foster been so inclined, RKO could have built a profitable series around the adventures of devil-may-care Robert Crane.