The novel "Fantaisie" takes place in 1946 post-war Europe, following Jan Orlinski, a former Polish RAF pilot, and his lover Sophie Gordon. Jan takes a job flying cargo missions from Paris to the Belgian Congo for a mysterious employer named Gerston, transporting what he believes is cobalt ore. Meanwhile, Sophie, who was previously exiled from Britain for unwittingly helping her Nazi-sympathizing father during WWII, is recruited by British Intelligence officer Herrington to feed disinformation to Soviet agents in Paris. She agrees, hoping to earn back her British citizenship and create a better life for her and Jan's young daughter, Maria.

The story takes a dramatic turn when Sophie disappears, taken by Soviet agents to Sachsenhausen prison in East Germany. Jan embarks on a dangerous rescue mission into Soviet-controlled territory, making unlikely allies along the way. Through determination, ingenuity, and help from his newfound allies, Jan manages to orchestrate a daring rescue of Sophie and Henrik. The story explores themes of redemption, trust, and the moral complexities of the immediate post-war period. It weaves together historical elements like Operation Bernhard (the Nazi counterfeiting operation), the Soviet atomic program, and the exploitation of African resources during the colonial period.

The novel concludes months later in England, where Jan, now working for British European Airways, conducts one final covert mission to help those who aided in Sophie's rescue.