In 1280, Edward I of England, known as "Longshanks", conquers Scotland following the death of the Scots' king, who left no heir. Young William Wallace witnesses the aftermath of Longshanks' execution of several Scottish nobles, then loses his father and brother when they resist the English. He leaves home to be raised by his uncle, Argyll.
Years later, Longshanks grants his noblemen land and privileges in Scotland, including jus primae noctis, while his son marries French princess Isabelle. Meanwhile, a grown Wallace returns home and secretly marries his childhood friend Murron MacClannough. Wallace rescues Murron from an English soldier, but Murron is subsequently captured and executed. In retribution, Wallace and the locals overthrow the English garrison, beginning a rebellion that soon spreads. Longshanks orders his son to stop Wallace while he campaigns in France. Wallace defeats an English army sent by the prince at Stirling, then invades England by sacking York. He also connects with Robert the Bruce, a contender for the Scottish crown.
Upon returning to England and confronting his son, Longshanks sends Isabelle to negotiate with Wallace as a distraction from the arrival of Longshanks' forces. Meeting Wallace, Isabelle becomes enamored with him and warns him of Longshanks' plans. Wallace faces Longshanks at Falkirk. During the battle, nobles Mornay and Lochlan withdraw, having been bribed by Longshanks, resulting in Wallace's army being overwhelmed. Wallace also discovers Robert the Bruce had joined Longshanks. After helping Wallace escape, Robert vows to not be on the wrong side again. Wallace kills Mornay and Lochlan for their betrayal and foils an assassination plot with Isabella's help. Wallace and Isabelle spend a night together, while Longshanks' health declines. At a meeting in Edinburgh, Wallace is captured. Realising his father's responsibility, Robert disowns him. In England, Wallace is condemned to execution. After a final meeting with Wallace, Isabelle tells Longshanks, who can no longer speak, that his bloodline will end upon his death as she is pregnant with Wallace's child and will ensure that Longshanks' son spends as short a time as possible as monarch. At his execution, Wallace refuses to submit, even while being disemboweled. The magistrate encourages Wallace to seek mercy and be granted a quick death. Wallace instead shouts, "Freedom!", while Longshanks dies. Before being beheaded, Wallace sees a vision of Murron in the crowd.
In 1314, Robert, now Scotland's king, faces the English at Bannockburn, and implores his men to fight with him as they did with Wallace. After Wallace's sword is thrown to land point-down in the ground, Robert leads the Scots to a final victory.
