At the height of the First World War, Emily Grey finds herself far away from the action, collating Swiss rubber imports in a hut in the middle of St James’ Park. Summoned to MI6’s Whitehall headquarters, Emily learns that her talent for languages is needed elsewhere and she is despatched to Bern to debrief Fritz the Ritz, an agent reporting on the wartime activities of German industry. However, when she discovers that Fritz the Ritz may not be all he claims to be, she is led to the door of an import-export dealership in Lausanne and the unassuming couple who run it.

Could they really be at the heart of a network that threatens the lives of millions of Allied soldiers? And, if they are, can Emily, and her ever-eager partner Nigel Nisbet, stop them before they go too far?