Jackson drags Lydia off into one of Stiles’s rooms for a private discussion about his house key. Needless to say, Lydia is still processing her ordeal with Peter. She’s still under the impression the alpha is running around in the woods somewhere. A bead of sweat and her heavy breathing betray her when Lydia tells Jackson she doesn’t know where his key is.
A trio of werewolves stands outside Stiles’s house as Allison texts Scott. The werewolf is returning the ripped pads to Danny ― who reminds his teammate that someone else was wearing the equipment when they tore. Danny was in goal.
A quick shot of Jackson’s home movie ― which Danny has been restoring all episode ― reveals what happened the night of the full moon. Jackson sits up, shirtless and with glowing yellow eyes. Thank goodness Danny looked away from the monitor!
Derek, Erica, and Isaac wait outside Stiles’s house. Allison decides to text her dad. Although discovering her whereabouts means Mr. Argent will know his daughter is dating Scott again, Allison has to make the sacrifice; the werewolves are prepared to kill Lydia.
The redhead has her own problems to deal with. Jackson is furious that she erased his tape, though she insists she doesn’t know what he’s talking about. “I hate you,” she tells anger-issues Jackson after returning his key ― which she was wearing around her neck. Jackson knows better, wipes away her tears, and kisses her. Uh-oh. Is it time for shapeshifter sex? Basically ― only it’s Jackson whose neck is all scaly.
As Stiles and Allison debate how to handle the pack of werewolves outside, they realize they’ve misplaced one. Isaac. Oh, he’s inside the house ― with his glowing eyes.
Lydia and Jackson are making out when a sound from downstairs interrupts them. All of a sudden, Jackson feels the back of his neck and collapses. Lydia has no idea what’s going on, and Allison runs upstairs to tell her someone’s trying to break in. Maybe it’s time to clue Lydia in that there are lizards and werewolves gallivanting about town?
When Lydia returns to the makeout room, Jackson is gone and the window is open. She proceeds to call the police, which is normal behavior. Good job, Lydia. Downstairs, Allison calls for Stiles. “It’s here,” she says when she notices the dripping venom.
Stiles doesn’t make it to Allison in time. Erica kicks open door and tells Allison, “This might make me sound like kind of a bitch, but I’ve always wondered what it’s like to steal someone’s boyfriend.” Then the werewolf neatly catches the arrow the female hunter shoots at her. Unfortunately for Erica, Allison has laced the weapon with venomous goo. Allison gently pushes the hair away from a paralyzed Erica’s face and whispers, “I thought you were psychic… bitch.”
Outside, Derek and Boyd hear a lot of crashing and groaning. When Scott arrives, Derek says the younger werewolf isn't an omega but an alpha of his own pack. Both hear sirens, then look up to see the lizard monster perched on Stiles’s roof. A minute later, Lydia stumbles out of the house. “Will someone please tell me what the hell is going on?” she asks. At the same time, Derek and Scott realize the creature is Jackson.
Lizard Jackson puts his talons against the window of a truck. So does driver. Is it another monster? The kanima sees its reflection and runs away.
Next week, killing Jackson will solve everyone’s problems, right?
In an experiment of dubious origins, Mr. Harris tells the students they can eat the crystal they just created over the last five minutes. Don’t do it, Lydia! She does it. The boys are very ineffective at stopping her. Nothing happens (a.k.a., Lydia doesn’t fall over in a paralyzed faint).
Uh-oh. Lydia has passed the test. Or maybe she’s failed it. Either way, Derek waits, menacingly, outside the school. Though she’s safe with hordes of students around, Allison, Scott, and Stiles are worried about what will happen to Lydia once class lets out. Lydia’s friends attempt to concoct a scheme that doesn’t involve scouring a 900-page book written in archaic Latin. Scott decides to try and convince Derek to spare Lydia’s life, but he wants Allison to stay safe. Naturally, Allison pulls out her crossbow to prove she’s a badass, werewolf-healing or no. The couple has a tender moment where Scott tells Allison to call her dad if she gets in serious trouble — even if it means him finding out his daughter is still dating a werewolf. Ruining the moment, Stiles almost shoots Scott, but he catches it the arrow.
Thank goodness. Lydia is getting the help she needs. At the guidance counselor’s office, she’s faking normal via Rorschach test. If everything looks like a butterfly, that means you’re well-balanced, right? Not according to Ms. Morrell, who thinks one of her ink blots looks a lot like a wolf.
The weird triumvirate of Jackson, Danny, and photographer Matt is congregated in the library. Matt tells Jackson that the movie-editing culprit had access to his house and knew how to loop his video footage. After the shutterbug leaves, Jackson calls out his friend for crushing on the camera-toting cutie. It doesn’t matter, says Danny, who is the only observant one in the group, because Matt is completely obsessed with Allison. OMG, Danny is the Velma of Beacon Hills High School. Why doesn’t anyone ever listen to Danny? Anyway, Jackson thinks Lydia is the one who’s edited his amateur monster movie.
The French teacher turned guidance counselor helps Allison decipher the kanima page in her bestiary. “Like the wolf, its power is greatest at the moon’s peak. Sounds like a werewolf,” says Ms. Morrell and laughs. Whatever, lady. We don’t trust you. Keep reading. “While the wolf seeks a pack, the kanima seeks a friend, says Ms. Morrell. “A friend? what does that mean?” Allison wants to know. When Ms. Morrell suggests the creature is lonely, Allison realizes the reptile is living in a teenage wasteland.
Scott meets Boyd and Derek on the lacrosse field. Lydia’s different, he tells them, but both believe she’s the lizard. She’s killed people, Derek reminds Scott. “It happens rarely, and it happens for a reason. Sometimes the shape you take reflects the person you are,” says Derek. When Scott suggests Lydia might be immune, Derek disagrees. He’s never seen it or heard of it. “What about Jackson?” Scott asks.
It’s then that Scott realizes Derek was hoping his bite would kill Jackson. Scott has a theory: Lydia’s immune and passed it on to Jackson. Regardless, Derek can’t let her live and has already sent his minions to dispose of her.
In a classic bait and switch, Erica and Isaac are lured into the library while Stiles, Allison, and Jackson haul Lydia off campus in the jeep. Then the foursome hunkers down at Stiles’s Meanwhile, Scott is stuck in a discussion about the duties of a captain co-captain and how to take care of equipment. En route to returning the torn lacrosse pads to Danny, Matt snaps a picture of Scott and his crazy eyes. The photog has noticed only Scott’s beautiful peepers throw off lens flares.
In the locker room, Jackson is lifting weights — a million pounds, probably. He’s crazy strong, remember? Danny is spotting his bestie, but actually, Jackson is struggling. “I should be able to do twice that,” Jackson pouts. Danny doesn’t want to hear it and hits the shower, telling Jackson not to kill himself. Despite his lack of werewolf strength, the boy has the ears of a supernatural. He can hear the water dripping from remarkably far away. When Jackson tries to lift the bar again, someone lifts the weight off — and chokes him. It’s Erica. Jackson got whooped by a girl!
Is this some strange werewolf initiation ceremony? After Jackson is led to Derek, the alpha questions the lacrosse player about what happened during the full moon. Nothing, Jackson swears. Derek tells Jackson he’s lying and slips on black leather gloves. Nothing good has ever come of a sinister man slipping on black leather gloves. Isaac laughs when Jackson says he taped himself not transforming into any kind of monster. Instead of letting Jackson slip off to get the proof, Derek flashes a mirror shard.
“You know, Jackson. You’ve always been kind of a snake,” Derek says. “Snakes can’t be poisoned by their own venom.” The werewolf pours liquid from the mirror into Jackson’s mouth. Jackson drops and convulses. Is Jackson dead? Nope, just paralyzed. “You’re still a snake, Jackson. You’re just not the one we’re looking for,” Derek tells him. Oh, we get it. He’s being metaphorical.
Post-paralyzation, Isaac tells Jackson he needs a favor. The next scene shows Jackson explaining to Stiles’ dad that he didn’t see Isaac arguing with his father before the latter’s murder. The sheriff isn’t happy.
Before econ class, Stiles tells Scott that a Rebel Without a Cause-looking Isaac has been released based on Jackson’s new testimony. That was fast. The boys have also discovered that Google doesn’t know everything: The only kanima they’ve found is a rare jaguar that goes after murderers. The lizard monster would be so much cuter if it were a jaguar.
Thanks to his super-hearing, Jackson knows all about the kanima. With all these new pseudo-supernaturals around, Stiles and Scott need to learn to talk in code. During the coach’s class, Jackson tells Scott and Stiles about Derek’s little lizard test. He also reveals that Erica and Isaac are planning on tackling Lydia during chemistry class.
Stiles isn’t entirely convinced his would-be boo is a murdering monster. The creature is 100% evil, but Lydia is only 50–60% evil. Something’s wrong with the redhead, though. Once again, she hallucinates about Peter. (Someone’s obsessed!) When she finally comes to, Lydia is sweating and has written “Someone Help Me” backwards on the chalkboard. Another trip to the guidance counselor is clearly in order.
Scott and Stiles slide into the chairs on either side of Lydia in chemistry class. Basically, Erica and Isaac are out to slip her some monster venom. There’s a high school version of musical chairs where everyone swaps lab partners at random intervals. It’s an ingenious way of getting everyone to talk to each other but a horrible way of conducting science. Shame on you, Mr. Harris. During the brief period of time they’re seated next to each other, Erica and Scott do zero chemistry, though she does try to see if there’s any between them. She rubs his thigh while he implores her to leave Lydia (and his hamstrings) alone. Before their speed dating science round is up, Erica hints that she doesn’t buy Allison and Scott’s breakup and flashes her yellow eyes at him, saying she’s exactly his type.
In the next pairing, Scott sits with Lydia, and Isaac reveals he wants Lydia dead even if she doesn’t sprout scales: She turned him down for a date in ninth grade. Stiles suggests he get a poetry book and journal his feelings, but Iaac would rather murder than emote.
Next swap! Isaac sits next to Lydia, and Erica tests Allison’s Kinsey scale rating by digging her nails into the hunter’s thigh and suggesting the star-crossed lovers won’t last. Then she invites Allison to a girl fight.