Eye of the needle - Ken Follett

Set in 1944, Eye of the Needle follows the story of Henry Faber, a German spy operating in Britain. Faber is a skilled and ruthless intelligence officer, codenamed "The Needle" because of his ability to slip through Britain’s defenses undetected, like a needle threading through fabric. His mission is critical: to gather vital information about the Allies' plans for D-Day, the invasion of Normandy, and to pass it back to the Nazis. He possesses knowledge that could change the course of the war, and he’s willing to go to any lengths to complete his mission.

Faber’s life takes an unexpected turn when he is stranded on a remote Scottish island after his escape plan goes awry. While on the island, he encounters Lucy, a young woman who lives there with her husband, David. David is an invalid, confined to a wheelchair due to a war injury, leaving Lucy isolated and vulnerable. She and Faber develop an intense relationship, and Faber takes advantage of her loneliness, seducing her.

However, the situation becomes complicated when Faber’s secret identity is inadvertently discovered by Lucy. She becomes entangled in a deadly game of cat-and-mouse, as Faber realizes that his cover is blown and that Lucy might pose a threat to his mission. As the story unfolds, Lucy is faced with an agonizing decision: whether to protect Faber and stay loyal to him, or expose him to the authorities to save her country and her husband.

Faber's deadly pursuit to finish his mission and escape the island collides with Lucy's growing suspicion and desire for justice, creating an intense narrative of survival and betrayal.