After meeting him in person, Isabella becomes enamored of Wallace. Worried by the threat of the rebellion, Longshanks sends his son's wife Isabella of France to try to negotiate with Wallace as a distraction for the landing of another invasion force in Scotland. Robert is dominated by his father, who wishes to secure the throne for his son by submitting to the English. Wallace seeks the assistance of Robert the Bruce, the son of nobleman Robert the Elder and a contender for the Scottish crown. Wallace leads his army to victory at the Battle of Stirling Bridge and then destroys the city of York, killing Longshanks' nephew and sending his severed head to the king. Wallace rebels against the English, and as his legend spreads, hundreds of Scots from the surrounding clans join him. Longshanks orders his son Prince Edward to stop Wallace by any means necessary. In retribution, Wallace leads his clan to slaughter the English garrison in his hometown and send the occupying garrison at Lanark back to England. Wallace rescues Murron from being raped by English soldiers, but as she fights off their second attempt, Murron is captured and publicly executed. Meanwhile, a grown Wallace returns to Scotland and falls in love with his childhood friend Murron MacClannough, and the two marry in secret. Years later, Longshanks grants his noblemen land and privileges in Scotland, including Prima Nocte.

Young William Wallace witnesses Longshanks' treachery, survives the deaths of his father and brother, and is taken abroad on a pilgrimage throughout Europe by his paternal Uncle Argyle, where he is educated. In 1280, King Edward 'Longshanks' invades and conquers Scotland following the death of Alexander III of Scotland, who left no heir to the throne.The synopsis below may give away important plot points.

Is brave heart based on a true story