The idyllic night scene of the opening village is shattered when a scream rends the air. The elder doesn’t find anything until he opens a door and a catatonic man falls on top of him. Something moves out in the darkness, and the terrified elder shouts a challenge. Umm … bad idea methinks.

The elder’s wife travels to Camelot, where she visits her old friend Gwen. The woman–Mary–says she wouldn’t have bothered Gwen but there’s nowhere else for them to go. So Gwen brings Mary before Arthur, and the older woman explains three good men have taken ill with a strange sickness in Longstead village. They have no physician, and the illness is beyond their understanding. Arthur, of course, agrees to help because it’s his duty to protect the people of the kingdom.

Gaius can’t make the journey because there’s too many cases of sweating sickness. So he suggests that Merlin go instead, an idea which takes some convincing. Arthur believes Merlin can’t find his own backside half the time. But Gaius presses the issue until at last Arthur consents. Huzzah! Predictably, Merlin’s concerned he isn’t ready. Gaius gives the boy a pep-talk, and reminds him the fate of the kingdom is in his hands every day. Merlin’s still not convinced, but Gaius hands over his medicine bag while Merlin’s packing. This is a Big Deal to say the least.

Merlin, Gwen, and Mary arrive at the village accompanied by Leon, Elyan, and the other knights. John, the elder, is disappointed at Merlin’s presence. He expected Gaius, not some boy, and is reticent even though Gwen says Merlin was appointed acting physician by King Arthur. The three sick men are all alive, but only just. Merlin examines them and then sends Gwen and John off to get supplies. He casts a brief spell on one; I don’t know what’s supposed to happen, but Merlin looks downright terrified when he stands up.

That night while reading, Merlin hears a creak and something flits passed the window. So what does Merlin do? Grabs a fishing rod and goes to investigate. Sigh. Idiot. He sees something move, and then come at him! It’s just Gwaine though, who chuckles at Merlin’s choice of weapons. After the knight departs, Merlin looks around for a bit more and then heads inside.

The morning brings news that the treatments had no effect. Merlin tells John there’s a force at work here he doesn’t understand. The elder wonders aloud if it’s sorcery, and Merlin acknowledges that as a possibility. Then John reveals he felt a presence in the air the night he found Aldriff (dude from the opening). Something evil. Oooeeeooo … I got chills!

Merlin needs Gaius to explain this, so he and Gwen head back to Camelot with the knights. On the way, they come across a group of bandits molesting a woman. Against orders, Gwaine leaps into action to save the woman. I’ve got a feeling this is going to backfire on them somehow. The knights follow him–what else can they do?–and after the battle Percival finds the woman the bandits were tormenting. She appears dead, until Merlin touches her face and she screams bloody murder. Percival eventually calms her down. The girl introduces herself as Lamia. Merlin tries to examine her hands, but Lamia screeches and pulls back. Leon puts him aside and, after Lamia confirms she’s OK to ride, decides to get the heck out of there. Let’s see … strange girl saved from bandits. Her name is the title of the episode. Yeah this is going to backfire.

Leon finds a place to camp for the night. Merlin offers a hand to get Lamia off the horse, but she hisses at him. Percival shoves him away, hard, and tells him to stay away. Merlin’s well and truly confused now, despite Gwen’s assurances Percival didn’t mean to be so nasty.

That night, Percival hears a woman sobbing. He finds Lamia and comforts her, but doesn’t see her eyes go yellow. She pulls back, probably to do something evil, and then a twig snaps and Percival’s on his feet. It’s only Merlin though. He offers water, but Percival helps Lamia to her feet and they walk away without speaking. Ruh-roh, Raggy.

Back at Camelot, Arthur is very worried. The party should have returned two days ago. Agravaine and Gaius try to assuage his concerns, but Arthur’s not having it. He confirms that Gaius’s work is done here, and declares they ride out at first light.

At the campsite, Lamia shies away from Gwen. Merlin watches this and ponders, until Gwen comes over and says the girl won’t eat. Then Leon declares they’re riding east with the rising sun, which confuses Merlin because Camelot is to the west. Apparently Lamia has asked to be taken home. Merlin really wants to get Gaius to figure out the sickness though. Gwaine declares Gaius can wait … and I get the sense Lamia’s worked some magic over the knights but not Merlin or Gwen. Curiouser and curiouser.

Merlin declares they were sent to help the people of Longstead. Leon gets angry and slings some nasty insults at Merlin. Gwen tries to intercede, but Elyan tells her to stay out of it. This shocks her into silence as the knights escort Lamia aside.

Arthur and Gaius stop when Arthur realizes there’s no birdsong in the forest. How very odd. A scout calls the king forward, and they come across a group of dead slave traders from the south. Their prison cart stands open, scratched by human hands. Whoever was inside did whatever they could to get out.

Someone groans, and Arthur rushes to the surviving man’s side. He asks Gaius if anything can be done for the man, and the physician says he needs time and room to work. So it’s decided the man comes with them.

Leon unhooks a waterskin to take to Lamia, but Gwaine tries to grab it from him. The two knights get into a shoving match while Merlin and Gwen look on. It might escalate, until Merlin shouts at them to stop. Leon shoves Gwaine on his way by, and the hothead draws his sword. They duel until Percival and Elyan pull the pair apart; Merlin’s furious and Gwen goes for the medicine bag. Lamia turns away and smiles evilly. Everything’s going to plan I guess.

Arthur and his party are in Longstead at last. Agravaine reveals Merlin and the others left yesterday morning, heading toward Camelot. Arthur is convinced something must have happened. Gaius, meanwhile, confirms Merlin’s fears to the village elder. Sorcery is indeed at work with the illness.

At camp, Merlin and Gwen compare notes about the changes in their friends; Leon and Gwaine have never fought like that before, and Elyan is a completely changed man. Merlin figures out the answer is Lamia, but Gwen doesn’t believe it. How can such a young girl affect grown men like that? Umm … how’s magic sound?

Gaius informs Arthur the southron confirmed his position as a slave trader. They were transporting a girl south when fights and quarrels broke out regularly among their party. They blamed the girl, who eventually escaped and killed them all. Gaius explains the girl was a Lamia, a creature birthed by mixing the blood of a young girl with that of a serpent. Able to suck the life from a man with a single embrace, the Lamia can transform from a girl into a hideous beast at will. If the creature begins killing, it will not stop … and Gaius confirms it’s still out there somewhere.

At camp, Elyan hears a strange hissing noise. He investigates and discovers Lamia wandering around. She sashays closer, plants a kiss on him, and Elyan soon falls to the ground. Once he drops, we see Lamia’s yellow serpent eyes gleam in the night.

In the morning everyone wakes to find Elyan gone. The men spread out to find him, and Gwen stays with Lamia. The girl tells Gwen not to worry … they’ll find her brother soon enough. Ominous much?

Arthur and his team find tracks heading east not more than a day old. So they follow, figuring it must be Merlin and the knights. Good call on that score.

The knights cart a comatose Elyan back to camp, and Gwen suitably freaks out as a result. She whispers to Merlin that she knows Lamia is at fault, and the wizard declares they need to get back to Camelot. Lamia interrupts that there’s a castle nearby. Merlin doesn’t want to go; he knows they need Gaius. Except Leon says Merlin and Gwen’s only choice is to go with the knights or not.

As they ride toward the castle, Gwen suggests they try reasoning with the knights. Merlin knows they won’t listen while they’re under Lamia’s spell. Arthur is their only hope now. They’ve been gone too long and he must know there’s something wrong. Gwen’s unsure of how he’ll find them, and Merlin declares they’re just going to need to help him out.

Arthur stops at a set of tracks that just ends. Agravaine tries to convince the king he’s wasting time. For all they know, Merlin and the others are back at Camelot by now. Except Arthur knows they’re not, so he orders the men to fan out and see what they can find.

The scene switches to Gwen tying a strip of cloth to a tree while Merlin guards her back. They come at last to a ridge overlooking the castle.

While searching, Agravaine sees a track and scratches it out before covering it with a branch. Jerkface.

Lamia leads them into the basement of the castle past a broken grate. Merlin tries to reason with Percival, but the big man tells him they’ve no interest in his opinion. Ouch. Such nastiness comes with that spell.

They’re halfway down a rocky tunnel when the torches go dark. Merlin lights his with magic and then comes forward and lights Leon’s as well. Then they notice Lamia has gone, and Leon runs off in search of her. They come to a gigantic room full of skeletons. Clearly it’s a trap, and Merlin’s the only one to say Lamia brought them into this dangerous place.  He doesn’t stop saying it until Leon throws him into a wall.

They find a place at last for Elyan, and Leon says he and Percival will search for Lamia. Before they leave, Leon growls that Merlin is to stay there and do what Gwaine says. Ooo … someone’s really under a spell.

Agravaine again tries to convince Arthur to turn back and they’ll try again in the morning. Arthur maintains they could be dead by then, and despite Agravaine’s assurances decides to keep going. After all, Gwen’s with them. And we all know how Arthur feels about her.

Gwaine heads out to get more firewood. Merlin offered to go, but the knight got all in his face about the wizard apparently trying to tell him how to do his job. Gwen sits with Elyan’s head on her knees, and tells Merlin her brother might not make it if he doesn’t get help soon.

The three knights each hear hissing while they’re out searching. And of course they all separate and go off on their own. Sigh. Gwen ponders why only the knights were affected, and after Merlin says the victims have all been men she figures out there’s something special about Merlin that makes him immune. Uh how about he’s a super-powerful sorcerer? There’s a scream, and Merlin leaves to investigate. He calls softly for Gwaine, who he sees down the hall. Then he touches the knight, and the man falls comatose on top of him.

Arthur finds a piece of Gwen’s tunic tied to a half-broken tree, and gallops off thinking they’re close. Good thing too, because they soon find the castle.

Percival walks alone through a super-creepy hallway when he hears a woman crying. It’s Lamia, hiding curled up. She thanks Percival for finding her, and then plants a kiss on him. Leon finds Lamia standing over Percival’s prone body and rushes her. She knocks him for a loop, throwing him this way and that, until at last she can climb atop him and suck his life out too.

Merlin discovers them too late, and Lamia says she could’ve killed him any time. He challenges her to try, which makes her hurl him backwards. He then raises Leon’s sword with magic, runs her through, and throws her into the shadows. Then snake Lamia appears and gives chase. Gwen leaves her brother and joins the battle, running Lamia through with another sword. The beast doesn’t fall, however until Arthur appears and strikes the killing blow.

Everything ends happy, Arthur makes fun of Merlin for being saved by a woman, and the episode ends with a kiss between Gwen and our king. After, of course, he tells her that she’s an amazing fighter. Arthur sure is a sweet-talker isn’t he?

If you missed the previous episode be sure to read our ‘Merlin: The Secret Sharer’ recap.