Shortly before visiting the Grail castle in Branch VIII of the Perlesvaus, Lancelot is urged by a hermit to confess his sins; the passage is closely echoed in the Queste, where Lancelot is exhorted to repent the sins that have been revealed in his abortive encounter with the Grail at the ruined chapel (P, 3647–95; Q, 65:6–67:9). This chapter will take these parallel episodes as the point of departure from which to explore the complex relationship between sin and the Grail in the medieval romances, and the consequences of this relationship for the Grail hero in these texts. By focusing on the location of sin, or rather the impossibility of its ever being adequately locatable (and therefore fully policeable), I shall examine some of the practical methods available for handling sin in medieval society, in juxtaposition to some more theoretical approaches to the concept of sin from modern perspectives such as that of Kristeva. Exploration of the manner in which the theory and practice of sin are represented in the Grail romances will demonstrate that the concept of sin might be conceived of as a religious thematization of the abject, as the condition of possibility of the very structures that seek to displace and finally to expunge it – most notably the act of confession.