In France in 1944, SOE agent Rosie Ewing has been shot by the Gestapo on her way to a death camp, having run off as a decoy in order that her fellow agent Lise can make an escape. One of them must survive in order to tell London of double agent Andre Marcheval's activities. Left for dead, Rosie is rescued by two men of the Maquis and taken to a safe house. Here, as she recuperates, she begins to form her plans to reduce the threat posed by Marcheval, and more immediately, to get in touch with London and inform them of her current situation. She learns that Marcheval's father has a factory some way away in which rocket casings are being manufactured. Now she must not only find Marcheval and eliminate him if necessary, but also stop these potential bombs from being made.