The title comes from 'knight's fee', a feudal system term used for a manor or land holding held by a knight, in return for providing military support to an overlord. The novel is set in the same general location as Sutcliff's Warrior Scarlet (1958) and the plot contains several references to this earlier work. 

The central figure is Randall, orphan son of a Breton soldier and Saxon mother who works as a dog-boy in Arundel Castle. He is taken home by Sir Everard d'Aguillon, who holds the manor of West Dean from his feudal overlord de Braose, and is brought up with Sir Everard's grandson Bevis.

The book follows the two as they grow up; when Sir Everard dies, Bevis becomes a knight and inherits the manor, with Randall as his squire. Bevis and Randall are part of the army led by Henry I against his older brother Robert Curthose in a campaign that culminates in the 1106 Battle of Tinchebray in Normandy.