Sexton Blake and Tinker foil criminal plot connected with the Tongs, and master-minded by "famous stamp collector" and millionaire.

Set on Blackpool’s Golden Mile, Jim (Douglass Montgomery), a once promising scientist, sets up in business as a patent medicine man selling hair tonic at the fair with his ex-army colleague Dan (Ronald Shiner). Following a fight with local hoods over pitch spaces, Jim falls for Jane (Hazel Court), the girl on a nearby candy floss stall. The two begin dating but Jim fails to mention he is already married.

In Britain, a man with a shady past uses his antiquities shop as a front for smuggled diamonds but his young shop-assistant starts blackmailing him, leading to murder and to a police investigation.