When learning becomes a fight for survival, class is in session. After surviving the siege at Warden’s Rest Academy, Alden Voss hopes teaching Strategy and Defense will be less deadly than his janitorial days. But his first class trip to Fort Sentinel turns lethal when a heavily armed scout force ambushes the isolated stronghold. With communication severed and the veteran Centurion defenders overwhelmed, Alden and his students must put their lessons to the ultimate test. Outnumbered and facing powerful magic, Alden must transform his students from learners to fighters—or Fort Sentinel will become their grave. The attackers picked the wrong field trip to disrupt.