William Thatcher (HEATH LEDGER) is a young squire who's always dreamed of being a champion knight who competes in prestigious jousting tournaments. Unfortunately, he was born the son of John (CHRISTOPHER CAZENOVE), a poor thatcher, and thus seems unlikely to leave his station in life.
He gets that chance, however, when his master dies and he brazenly takes his place in a tournament that he wins. Buoyed by his success, William tries to convince his two friends, Roland (MARK ADDY) and Wat (ALAN TUDYK), that they could help him train and become a champion. Knowing their place in life, they try to remind William that only knights can compete, and that they'd never get away with such a ruse.
That changes when they run into Geoff Chaucer (PAUL BETTANY), a write with some serious gambling debts who agrees to forge some entry papers for William in exchange for their help. Donning the name and guise of Ulrich von Lichtenstein of Gelderland, the unlikely team trains and enters William into a nearby tournament where he places second in the jousting contest to Count Adhemar (RUFUS SEWELL), the nefarious reigning champion.
Entranced by the lovely maiden Jocelyn (SHANNYN SOSSAMON), and equipped with new and revolutionary armor from outcast blacksmith Kate (LAURA FRASER), William continues on his quest to become champion of his sport. As he continues to woo Jocelyn and has a chance meeting with Colville (JAMES PUREFOY), a.k.a. Edward, the Black Prince, William does what he can to make sure that he can defeat Adhemar upon their next competitive meeting.