The Queen summons Sir Launcelot to her room, meanwhile Sir Modred and Sir Aggravayne surround the room demanding that Launcelot come out.
Sir Mordred faked his father's death, making himself King. King Arthur is in France the whole time and comes back only to find out this news. King Arthur engages a battle with his son and Sir Gawain dies in battle. Sir Gawain's ghost comes back to tell him not to fight Sir Mordred.
King Arthur and Sir Mordred kill each other in battle leading King Arthur to be buried. Some believe he will come back some day.
The King charges the Queen with treason leading to Launcelot rescuing her and killing most of King Arthur's men. Which leads to war being declared on Launcelot. Also he is banished from England.
Sir Launcelot finds out about the news and weeps because he realized he was too late. He then goes to live with the Archbishop. He finds out Queen Gwynevere died as well and buries her beside King Arthur. Later on Sir Launcelot dies as well.
Sir Gawain convinces Sir Arthur to go to France and start a war with Launcelot. Sir Gawain challenges Launcelot to a joust. Sir Gawain repeatedly loses and Sir Launcelot continues to give him mercy.