American-born spy and code-breaker extraordinaire Maggie Hope must solve a baffling series of murders among a group of captive agents on an isolated Scottish island as the acclaimed World War II mystery series from New York Times bestselling author Susan Elia MacNeal continues. A series of baffling murders among a group of imprisoned agents threatens the outcome of World War II in this chilling mystery from theNew York Timesbestselling author ofMr. Churchill's Secretary. November, 1942. World War II is raging, and former spy Maggie Hope knows too much- what the British government is willing to do to keep its secrets, who is lying, who the double-crossers are. She knows exactly who is sending agents to their deaths. These are the reasons Maggie is isolated on a remote Scottish island, in a prison known as Killoch Castle. When one of her fellow inmates drops dead in the middle of his after-dinner drink-he's only the first. As victims fall one by one, Maggie will have to call upon all her wits and skills to escape-not just certain death . . . but certain murder. For what's the most important thing that Maggie Hope knows? She must survive. Praise forThe Prisoner in the Castle "The colonel sums it up best on page ten- 'If you take a pretty girl and teach her how to kill, it can cause problems.' Not just problems-electrifyingaction and nonstop surprises. I loved this book!"-R. L. Stine, author of the Goosebumps and Fear Streetseries "Another literary tour de force . . . From the book's perfectly calibrated plot to its incisively etched characters, everything is handled with perfect finesse by the author."-Poisoned Pen Newsletter "One pleasure of a mystery series is connecting with a character that changes and grows with each novel. . . . Maggie's intelligence and loyalty to the war effort continue to evolve in Susan Elia MacNeal's series. . . . Solid twists keep the plot ofThe Prisoner in the Castlechurning until the surprise finale."-Associated Press "A mystery . . . tailor-made for readers in the post-election, #MeToo era. . . . If you love a tricky puzzle that requires you to keep track of multiple alibis over time, this is your summer read."-The Washington Post "Evocative."-Publishers Weekly "MacNeal uses Agatha Christie'sAnd Then There Were Noneas a framework for a character-driven mystery/thriller that successfully emulates the original."-Kirkus Reviews