Assassin's Apprentice (Assassin's Apprentice #4)

Normally, finding an assassin at the foot of your bed in the middle of the night is a recipe for disaster. But for Fitz, it turns out to be a doorway into a whole new world. Soon, Fitz's life becomes split between his daylight duties with Burrich and his nocturnal lessons deep below the Keep. But when his new master sets him a seemingly impossible task, the boy will find his loyalty stretched to the breaking point.