A simple class trip turns into a massive medieval mess. Wiglaf and his classmates head to a local home for retired knights, expecting a quiet afternoon of playing games with the elders. Instead, they discover that the legendary Sir Lancelot is living there, and he has officially decided he is done with hacking, whacking, and adventuring. The timing could not possibly be worse. Grizzlegore, the world's oldest living dragon, has just arrived in the neighborhood and is already stirring up serious trouble. The students know they cannot defeat this ancient beast on their own. Erica, Wiglaf, and the rest of the gang must find a way to inspire Sir Lancelot and his retired friends to get back into fighting shape. It will take a tremendous effort to convince the aging heroes to pick up their swords one last time and save the school from complete destruction.