After all the poison trouble from Evil Gwen last week, it’s strange that she would start this week’s adventure generously pardoning a young lad caught wandering around Camelot in the middle of the night. He’s been catching frogs, you see. Everyone catches frogs in Camelot in the middle of the night when they’re teenagers.
And it seems the thought of frog-catching has made Gwen feel quite randy, and she sends Merlin off to run her a bath which they have a bit of a royal frolic.
While Merlin boils the water, the lad, Daegel, turns up at the kitchen, showing his druidic mark and asking for help for his sister, who lies dying a half-day’s ride from Camelot. Merlin is unwilling to help at first, but eventually concedes, leaving Gaius to attend to his duties. This will definitely go well.
Oh, apparently not. Arthur is trying to prepare for the arrival of the Sarrum of Amata, and needs Merlin’s help. Gaius tells him Merlin’s gone off herb-hunting, but Arthur concludes he’s drunk. Arthur, who clearly is not used to dressing himself, makes Gaius help him, with not entirely successful consequences (he puts Gwen’s nightie on instead).
On the trial, Merlin tends to Daegel’s wounds and gives him breakfast, and the two get talking. It turns out he and his sister are orphans.
Back in Camelot, Evil Gwen is out and about, leaving a note at the foot of a tree for Morgana to read. Arthur and Gaius discuss Sarrum’s fearsome reputation, and how hard it will be to forge an alliance against Morgana. But they resolve to try. He arrives in Camelot, haughty and smug, and demanding a tournament.
However, it turns out that Daegel is not all he seems. His druid mark has worn off, and, hello! Is that Morgana? It IS! She knocks him out with magic, then puts some nasty-looking black poison in his mouth, then knocks him into a hole and leaves him for dead. Then she pays off Daegel, and heads back to cause more trouble for Camelot.
Arthur and the Sarrum are discussing Morgana over dinner. Sarrum explains that he managed to capture Morgana by exploiting her love for her young dragon, locking the two of them in a well for two years, refusing to let them out even while the dragon grew too big for the walls.
Gwen leaves, upset by the tale, and meets Morgana in the woods. It seems Morgana’s plan is to create conflict between Arthur and Sarrum, and Gwen will be the agent of disruption, retaining the throne and bringing Morgana back when the two have destroyed each other.
Meanwhile, Merlin attempts to overcome his poison by magic, and fails. He is eventually joined by a returning Daegel, who has had an attack of conscience. Merlin sends Daegel to find the herbs he needs to make the tincture that may cure him, but he’s running out of time. And even when the herbs are found and administered, Merlin soon becomes desperately ill.
Next day, Arthur fails to fight off Sarrum’s best champion, and Gwen takes the opportunity to suggest, in a quiet corridor, that Sarrum should take over the kingdom. When they meet later to discuss it, Gwen offers Sarrum a third of Camelot’s lands in exchange for her place on the throne once Arthur has been killed. Gwen will grant safe passage to Arthur’s room for an assassin, and that’ll be that.
Back in the woods, Merlin finally comes to. Daegel tries to apologise for hoodwinking him, and reveals that Morgana is planning to kill the king. The pair start their long and hazardous journey back to Camelot, only to be surrounded by bandits. Nothing a little Merlin magic can’t sort out, of course. And on they go, with Daegel tending to Merlin’s wounded leg as they go. It turns out he doesn’t have a sister, but his mother was magical, and was killed by Uther.
The next day, Sarrum appoints his champion to kill Arthur, and reveals his plan to depose Gwen too, given half a chance. Gwen is making up all sorts of stories to explain Merlin’s absence, and Gaius has had to dress Arthur again. No one is happy.
The two leaders assemble in the great hall, ready to formalise their alliance. But at the same time, Sarrum’s champion is readying his crossbow, and Merlin is rushing, hobbling through the corridors to try and prevent Arthur’s death. He finds an unlocked door up to the gallery, realises this is where Sarrum’s assassin must have gone, and follows. The champion shoots at Merlin, chucks a dagger after it, then knocks him down, and prepares his shot, only to be impaled by a magically-assisted walking stick. The assassin’s bolt misses Arthur and hits Sarrum instead, killing him. But Merlin’s victory is short-lived, as he realises Daegel was hit by the thrown dagger and is dying.
Once the explanations are over, Daegel has been buried (and no one seems to have told Arthur the truth about anything much), Merlin and Gaius resolve that something needs to be done about Evil Gwen. The question is… what?