King's Arrow: Crown & Covenant series #2

Agnus M'Kethe, a ready archer, guards sheep from scavenging crows. Loyal to his family, Agnus must match wits in a life-and death struggle against Highlanders. By faith, Agnus turns his beloved game of chess into a tool of victory. But desperate fear grips the Clan with an unexpected murder! Will Covenanters be found guilty? Angus's true test of manhood and marksmanship will come at the Battle of Drumclog.