'The Cheyne Mystery' delves into the thrilling world of mystery and suspense. In 1920, Maxwell Cheyne, a war veteran and writer, finds himself caught in a web of intrigue. After being drugged and robbed, Cheyne becomes entangled with a dangerous gang searching for a crucial letter. Determined to retrieve the stolen contents, Cheyne embarks on a perilous journey, aided by the brave artist Joan Merrill. As the stakes escalate, Cheyne narrowly escapes death and turns to Scotland Yard's brilliant Inspector French for assistance. Together, they unravel a cryptic code and follow a trail that leads them from London to the depths of Bruges and Antwerp, unearthing the secrets of a deceased German U-boat captain.