It has been five years since Stephen Staplehurst and Barabara Fielding foiled a villainous plot by an international gang of mail robbers. Since then Barabra has found success in the secret service and broken off her engagement with Setephen, who remains frustrated in the advancement of his career at the Post Office. When a fresh murder investigation suggests that the gang has restarted its nefarious activities, Stephen sees a chance to prove himself. Meanwhile, Stephen's sister begins to suspect that all is not as it seems. Who is the mysterious woman with whom her brother has been seen consorting? And why is he present at the scene of each new crime?
Origially published in 1929, this is a vintage thriller from the golden age of detection, and is a sequel to Austin Philips's earlier novel, The Man in the Night Mail Train.