With Sir Gwaine and his followers lost in the wilds near Ismir, the stronghold revived by none other than Morgana, Arthur knows that a rescue mission is the only possible course of action, but Gaius warns that a direct assault is exactly what Morgana is expecting. Gwen suggests Arthur and his knights take an alternate route, approaching Ismir from the west by crossing through the land of their ally, Queen Annis.
Annis is only too glad to grant safe passage to Arthur and his knights, and the evening's feast leads to merriment, which somehow leads to Merlin getting tricked into juggling for the Queen's pleasure. Arthur is shocked to learn his trusted servant has this skill, but the humiliation of being treated as a jester can't wipe one image from Merlin's mind: Before reaching Alice's castle, the rescue party came upon a village that had been sacked, and all its inhabitants dead. Merlin wandered on his own and came across man who sprang to life when Merlin touched a strange symbol on the man's wrist.
The man warned Merlin to take greater care than ever of Arthur, or the prophesy of Arthur's Bane would trap them all in its cycling destiny. He then showed Merlin a vision of Arthur in a terrible battle, being struck down by a dark-haired foe. The dragon tells Arthur that the symbol on the man's wrist was that of a Druid seer, and he should heed the words and vision well.
Gwaine and his company, meanwhile, have been captured by Morgana and put to work in the mines underneath her stronghold. She is searching for a mystical key that her adviser says will grant her access to worlds of knowledge, and she forces her captives to hack in the granite in search of it. One night, Gwaine spies a soft light coming from one of the uninhabited mining tunnels. Following it, he is surprised by Morgana's guards, beaten for wandering away, and left for dead. But as his body lies prone, a glowing blue figure approaches and incants a spell that heals Gwaine's mortal hurt.
As Arthur and his knights approach Morgana's castle, Merlin tries to get Arthur to turn back when they are sprung upon by Morgana's forces. Arthur is attacked and Merlin must carry him away to safety. Word of the ambush reaches Camelot, where Gwen realizes her trusted handmaiden, Sefa, has been feeding information to the enemy. As punishment for this treason, she sentences the girl - who did what she did in order to protect her sorcerer father - to death. Gaius and others look askance at Gwen's severity, but say nothing.
In a quiet dell, Merlin tends to the wounded Arthur who, the moment he awakes, insists on going after his men. Merlin breaks down and tells him of the prophecy he heard, but Arthur places no authority in it. As the two search for food, they fall into a trap, and are cut down by a band of ruffians. A dubious figure saves them from immediate death by saying that Lady Morgana must decide their fate. Arthur is grateful for the reprieve, but Merlin recognizes the face as the one who slew Arthur in the Druid's vision - and it is Mordred.