Al Roberts

Maggie Wells, the secretary of a private investigator who was murdered, is on her way to see Joe Mannix. The cab driver taking her there fails to follow the route to Mannix' office, and then attempts to shoot her, but she is able to escape.

Mannix is hired by a bank to search for Paul Gantry, an Australian sailor who stands to inherit a sizable sum of money. To find him, Mannix goes under cover at the waterfront posing as a sailor looking for any of his "shipmates" from a recently sunken freighter, the Harlequin, on which Gantry served as one of the crew.