Thematically and as a narrative technique, interlace, the complex weaving together of many different story-telling strands, comes to its full development in the intriguing conclusion of the Prose Lancelot. The Grail appears on the horizon and although Lancelot's love for Guenevere still makes him the best knight in the world, it becomes clear that this very love disqualifies him from the Grail Quest. Meanwhile, the adventures of a myriad Arthurian knights continue to be followed. This study explains how the interlace works and shows that it is the perfect vehicle for the relation of the events. It discusses the division of the narrative into threads, their interweaving, convergence and divergence, the gradual introduction of the Grail theme and its first climax (the begetting of Galahad), the distribution of information to the audience, the use of dramatic irony and emotions, and many other aspects of this major innovation in story-telling technique. Dr Frank Brandsma is Senior Lecturer in Comparative Literature (Middle Ages) in the Department of Modern Languages at Utrecht University.