The story begins in post-World War II London as Colonel Ralph Denistoun recalls a pre-war mission in Nazi Germany. While attending a dinner party, he notices a pair of gold earrings, which triggers memories of his past. The film transitions into Denistoun’s flashback, revealing how he and his fellow officer, Lt. Richard Byrd, were on a covert assignment to obtain crucial military secrets stored in a laboratory in Germany. During their mission, the duo encounters numerous challenges, eventually having to evade capture by fascist authorities. In their desperate bid to escape, the officers stumble into the camp of a Gypsy woman named Lydia.

Lydia is free-spirited and enigmatic, offering assistance to the fugitive Englishmen. She helps them disguise as Roma by altering their appearances, including convincing Denistoun to pierce his ears and wear gold earrings to complete his guise. Lydia’s knowledge of the land and local customs becomes invaluable as they navigate the perilous route back to safety while avoiding Nazi patrols. She and Denistoun develop a unique bond, affecting his worldview and inspiring him in unforeseen ways. As their journey unfolds, they face growing dangers and betrayals, creating tension between loyalty to their cause and personal desires. Denistoun's recount is a reflection of love and duty set against the dangerous backdrop of wartime espionage.