A fantasy adventure based on the Arthurian legend, the film tells the story of Sir Gawain, King Arthur's headstrong nephew, who embarks on a quest to confront the eponymous knight, a gigantic tree-like creature.

Antonius Block is a knight, who along with his squire, are returning home from the crusades. Black Death is sweeping their country. As they approach home, Death appears to the knight and tells him it is his time. Antonius challenges Death to a chess game for his life. Antonius and Death play as the cultural turmoil envelopes the people around them as they try, in different ways, to deal with the upheaval that the plague has caused.