Eagle Day by Robert Muchamore

During World War II, spymaster Charles Henderson recruits and trains a group of courageous youngsters, including the resourceful Marc Kilgour, to serve as covert agents. When information points to a dangerous German operation, the children are sent on a high-risk mission behind enemy lines to gather vital intelligence and sabotage enemy plans, forcing them to confront fear, test their loyalties, and grow up fast under relentless danger.

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