An average adaptation of an Edgar Wallace tale, this features Barr as a Scotland Yard investigator and Knox as a police doctor. They team up to find a mysterious killer, known only as "The Ringer" because he is a master of disguise. When lawyer Lawson receives a bouquet of flowers
informing him that he'll be dead in 48 hours, the cops get to work trying to uncover the killer. As the hours tick away, they learn that Lawson's secretary recently committed suicide, and that The Ringer holds the lawyer responsible. At the fated hour Lawson dies, but Barr exposes his partner Knox
as the murderer. Third of four film versions of Wallace's novel.