Still recovering from a Saxon attack (A Tail of Camelot), Camelot suddenly falls to a mysterious illness. As young mice Calib and Cecily set out on a voyage to find help, Lancelot's son Galahad seeks a cure within the fortress. Working together, the mice and their "two-legged" partners again triumph. Leung's retellings of Arthurian lore feature earnestly cheerful animals and children inspired by the famous legends.

In this sequel to A Tail of Camelot (2016), a mysterious plague threatens Camelot, forcing warrior mouse Calib Christopher to embark on a perilous mission to the magical isle of Avalon while young Two-Legger Galahad faces a formidable foe in King Arthur's malevolent nephew.The unexpected arrival of a sick squirrel-maiden seeking Avalon's healers to cure the deadly sickness infecting her village interrupts Camelot's Harvest Tournament and Calib's final challenges as a graduating page. Meanwhile, Arthur's accomplished, secretive nephew, Red, appears in Camelot with dastardly intentions, sparking 11-year-old Galahad's immediate distrust. Contagion rapidly spreads through Camelot, striking the strongest, depleting ranks of both mice and humans, puzzling healers, and prompting Calib and friend Cecily to search for Avalon while Galahad combs Merlin's Scrolls for a cure. Using the essential qualities of a mouse-knight, "bravery, strength, and wisdom," to fend off highwaymen, treasure seekers, and pirates, Calib and Cecily eventually reach Avalon, where the Lady of the Lake reveals what must be done to remove the curse on Camelot—where Arthur and Galahad are in peril as Red seizes control. Leung artfully weaves familiar Arthurian lore into Calib's and Galahad's personal tales of self-discovery as the nail-biting adventure explores themes of deceit, treachery, loyalty, and sacrifice. Spot art reinforces key motifs. More suspenseful, enthralling mouse-eye perspective on the Camelot legend. (Animal fantasy. 8-12)