For 135 years, the province of Xessus has been subject to a repressive regime, Riadsala’s Mercy. Xessans are not allowed to travel; they cannot learn history, geography, reading, writing, or how to fight. The best and bravest boys are taken for the king’s army, never to return. Laws are enforced by the magistrate, Xela. The armed Westwall Guard, stationed on the edge of the province, keeps everyone in line. Resistance will trigger an ancient order: The Mercy will end, and Xessus will be razed to the ground.

On his 16th birthday Lebasi, the magistrate's son, dreams of escaping from a life where everyone sees him as his hated father's son. A girl persuades him to break the Mercy: the brutal punishment from his father leads him to help start a revolution to overthrow the law. When he realises his father's life is in danger, his loyalties are tested - Xela is the only family he has, and is the only person who can tell him the truth about the mysterious disappearance of his mother when he was a baby.

Lebasi has to set out on a dangerous and illegal journey to save his father from the trap the revolutionaries have set. This is the first instalment of an extended story: The Warning, The Westwall Guard and Fire & Water will follow on from the end of The Magistrate's Son.