Book #2 in what is sometimes considered the Inspector Marshall series.
With the actual fighting of WWI on the fields done, the fighting over the Treaty of Versailles gets underway. Captain Bernard Newman must infiltrate a highly secret organization who would love to reignite the conflict.
Note: Marshall, now an Inspector with "the Special Section of Scotland Yard", is now temporarily stationed in Paris with the British Delegation to the treaty negotiations and works with Newman in his latest mission.