Lagu is a witch who practices dark magic. A mob from Monkchester lynched her in communal reprisal; Aodh McDuncan rescued her, and Egas, a cleric of Dian Cecht, cared for and healed her.
In Lords of York
In the gesta Lords of York, Lagu warns Egas about the crimes of More. She lives alone in a cave and performs rituals with serpents, devouring entrails. A fifteen-year-old boy discovers her and accuses her of witchcraft; his father Randal organizes a mob that lynches her brutally. About to be hanged, she is rescued by Aodh McDuncan and the Celts.
Later David, in an act of demonic madness, throws her off a precipice, but she survives.
Her brother Osporn had given her in forced marriage to the elderly Nycols O’Cush.