The story opens in 1934 on the Spanish island of Ibiza. Following an incident at a fiesta, Verity, a young English lawyer, is listed as a British spy by General Franco, the military governor of the island. She escapes just in time to avoid arrest.

Back in England, she returns to work in her father's law firm but friendships made in Spain begin to shape the course of her life. As the tumultuous events in Barcelona build up to the outbreak of the Spanish Civil War, she is increasingly caught up in these events. As the Civil War gathers pace and the chaos builds, it becomes apparent that only she may be able to carry out a daring rescue mission. She finds that she has to make a choice between staying at home in a safe job or casting aside all conventions and being drawn into the shadowy world of espionage. Can she both succeed and survive as a woman in a man's world?

The intricate threads of the story draw together a group of diverse characters in London and Spain whose lives come together in an explosive conclusion as Verity becomes the target for sabotage and final betrayal in a battle whose outcome is far from predictable.