In 1939 Germany, 15-year-old Sarah and her mother try to escape to Switzerland, but her mother is killed at a checkpoint. Blonde, blue-eyed, and a talented gymnast, Sarah has been trained by her actress mother to assume whatever identity she needs to protect herself, because she is a Jew. Then Sarah meets a mysterious man at the train station who turns out to be a British spy. Captain Floyd takes Sarah under his protection, but he sends her on a mission: infiltrate a boarding school for daughters of top Nazi officers, befriend the daughter of a scientist, and steal the blueprints for a bomb. There's a plot twist around every corner, slow reveals of Sarah's past, and multiple cinematic moments, including a harrowing race through the forest. German phrases (translated and well-placed in context) add verisimilitude to the narrative. Fast-paced, cleverly constructed, and with references to real-life heroes, heroines, and villains, this promising debut will appeal to fans of historical fiction and spy stories.

Killeen-s harrowing debut opens in August 1939, just after a 15-year-old Jewish girl named Sarah and her mother drive through a Nazi checkpoint in a German town. Sarah-s mother dies in the crash, but Sarah evades capture thanks to Helmut Haller, aka Captain Jeremy Floyd, a British spy. Jeremy is attempting to prevent one of Hitler-s scientists, Hans Schäfer, from building a nuclear bomb. He offers to help Sarah escape Germany, but she insists on joining his campaign. Posing as Haller-s niece Ursula, Sarah enrolls at Rothenstadt, a Nazi boarding school. Her mission-befriending Schäfer-s daughter, Elsa-proves more dangerous than either she or Jeremy imagined. Despite a dynamite premise, dizzyingly high stakes, and some devastating moments, Killeen-s tale falls short of its potential. While the story-s adult characters are complex and realistically flawed, Rothenstadt-s residents read like mean-girl caricatures, and the frequency with which the intelligent, empathetic Sarah refers to herself as a dumme Schlampe (-stupid bitch-) is off-putting and out of character. The book starts strong and ends with a bang, but the muddy middle highlights the paucity of plot. Ages 12-up. Agent: Molly Ker Hawn, Bent Agency. (Mar.)