Previously on Teen Wolf, Ms. Jennifer Blake, literature professor and resident Beacon Hills mistletoe expert, killed a bunch of randoms in groups of three to steal their collective powers, which: fine. Whatever. Moonmouth, etc. But then she kidnapped Melissa McCall and Sheriff Stilinski and tied them up in a druid tree basement and now we hates her, Precious! Stiles had an existential meltdown because his beautiful supergenius brain was tapped out of ways to save the city, a crisis made infinitely worse by the fact that Scott decided to join up with Deucalion when Stiles couldn't formulate a Plan B. Cora Hale died and died and died and came back to life and life and life, a couple of times because of unexplained voodoo and one time because of Stiles' magic mouth.

If a psychotic Celtic emissary absconds with your father and a pack of rabid alpha werewolves vamooses with your best friend, one thing you are always going to consider doing to calm yourself down is: making out with and/or punching Derek Hale in the face. Because you just know this is all his fault. Stiles finds himself in just such a conundrum in the wreckage of McCall General Hospital, where that super-storm has miraculously disappeared but also has left the hospital in shambles. Derek regains consciousness before Stiles is able to wallop him, and off they go to save the day in their various sexy ways.

Derek and Peter take Cora back to their loft where she just keeps on dying and puking up black goop. Derek thinks he feels as shitty as possible, and then Isaac shows up and shouts at him for spending all his days and nights making wounded werewolf love to a ritualistic killer while Boyd and Erica and Cora were getting the life beaten out of them and Isaac was roaming the streets in a wet t-shirt trying to summon up the courage to ask Scott to share his bed/pajamas. After Isaac clomps off in a semi-British huff, Derek decides he will do anything in the world to save Cora's life.

"Funny you should say that," croons Peter Hale, who is sitting in the shadows on the staircase ordering plunging neckline t-shirts in bulk from J. Crew.

Peter pulls a package of Reese's from his pocket and explains the way for Derek to save Cora's life is either to regurgitate food into her mouth and aggressively groom her, or engage in a familial energy exchange that will zap away Derek's alpha powers but spark black goop healing in Cora. "When have any of my awesome plans ever caused you heartache?" Peter asks, chomping down on a peanut butter cup. Derek hems and haws and broods and glowers and paces and flops around on the ground and decides yes, he will give up his alpha powers to save his sister.

On the one hand, this plays like some more of Peter's Machiavellian antics. But on the other hand, the full moon (and that darn power-sapping lunar eclipse!) is only two days away and Kali has promised to kill Derek if he doesn't join the alpha pack, but Derek can't really join the alpha pack if he's not an alpha anymore, so maybe this will save him? (On the third hand, maybe Kali's threat still stands even if Derek relinquishes his powers and so then it will be even easier for her to crush his skull with her feets if he's not an alpha anymore?) (Oh, if only there was a magical veterinarian in this town who could pull plans and information out of his own bunghole at his leisure just in time to save the day every day!)

Stiles hangs out at the hospital to try to run interference when the authorities arrive, but the coppers in question aren't Beacon Hills' finest. No, indeed. They are the FBI. Stiles has an apparent history of smartassery with the lead FBI agent who follows him around town all day asking him to 'fess up about the location of his missing father and also exchanging Seussical repartee with him. ("You have brains in your head." "You have feet in your shoes." "While you were away, your kid got some tattoos." "More dead John Does?" "Eh, you know what you know." "This town is still a freaky shitshow.") Stiles gets bored of the FBI guy pretty quick so he searches out the one person in town whose brain can actually keep up with his.

Lydia, of course, is the marvel I am talking about. She comes to school with that nearly-strangled scar still burning on her neck. What's amazing is that her mom was like, "I can help you cover up that thing with some hickey-masking makeup tips I learned from when I was a teenage whore." And Lydia says she's just going to leave it because she's proud of being a survivor, and her mom says she's proud that Lydia is proud. But at no point in their heartwarming conversation do either of them suggest that very nearly getting garrotted to death by your English teacher is a satisfactory reason for staying home from school for the day. Anyway, pretty much as soon as Lydia shows up at school, Stiles is stricken with a full-blown panic attack. Frankly, it's a miracle it's taken him this long to succumb to them.

Stiles bangs around against the lockers and limps up the hallway and finally ends up crashing into the locker room, with Lydia right behind him. They fall to the floor and she caresses his face and tells him to think about something besides how his dad and his best friend have both been kidnapped by mass-murdering lunatics. She tells him to breathe. He says he can't. She tells him to breathe again. He says he can't again again. So she lunges for him and crashes her lips into his lips and kisses him long and hard, until his spirit relaxes and his lungs start functioning properly. When they break the kiss, he is stunned and she is stunned and he thinks its one of her magical powers and she says it's just her IQ. She read in a book that if you hold your breath while you're having a panic attack, you'll stop panicking. So she kissed him. And she literally took his breath away.

He says she's smart. Her whole thing has always been overt sexiness and hidden smarts. Dudes compliment her body. Stiles compliments her brain. He says she's smart she and looks anywhere but at him because he took her breath away too.

They hit up Ms. Morrell's office, thinking hey, even if it's Snape, there's at least one Order member left at school, right? But Ms. Morrell isn't there. That girl from the pilot, Virgin Heather's party pal, she's in for some counseling, so she tells them to scram because "dead best friend" trumps "arborist art fetish." But then she realizes, like Stiles and Lydia realize, that Lydia has been drawing the same druid tree six hundred thousand times, over and over and over again all semester long, and since she's a human Geiger counter for death, that tree is probably where everyone's parents are being held hostage.

On the other side of town in the Argent penthouse, Isaac shows up and offers to use his claws while Allison and Chris use their frikkin' military-grade weapons stockpile to track down Ms. Blake and rescue Melissa and Sheriff Stilinski. Chris is all, "Sure, sure, right this way, kiddos. Right into this impenetrable bank vault." And then he handcuffs them so they can't get away and get hurt. And he offers himself up as the third sacrifice in the Guardians trifecta. Ms. Blake ties him up in the druid tree basement with Melissa and the sheriff, and they happily tell him all the ways he has been disarmed and possibly strip-searched in their presence. There's enough bravery and parental affection and general hotness in that murder cellar to power the sun.

Out in the woods, Ms. Morrell is running wide open trying to get away from Aiden and Ethan and Kali, who have been ordered by Duke to kill her because she is Bianca Lawson and it is illegal apparently for her to survive on any TV show ever.

She tosses up a ring of mountain ash to buy her some time to dangle some more tidbits of information in front of Scott before she dies. Like, for example, Duke killed Ennis even after Deaton saved his life. In fact, Duke kills pretty much everyone he comes in contact with. Also, he's totally afraid of Ms. Morrell because she's like Jennifer, whatever that means. Open wounds really get her going too? Just as she's working up to some potentially useful information, Duke throws his spear-tipped blind stick at her and it punctures her heart. Gorgeous black people really don't have a shot in hell at surviving in Beacon Hills, do they?

Stiles and Lydia and Isaac and Allison and Scott converge on Dr. Deaton's office to see if he's got any deus ex machina up his sleeve. And yes, my friends, he sure does. The way Allison and Scott and Stiles can save their parents is to sacrifice themselves in their sacrificial place. But, like, they only have to die for a little while. And yeah, completing the ice bath death ritual will also leave a ring of darkness around their hearts for the rest of their lives. And OK, sure, it'll also re-power that old druid tree which means every kind of beast and awful thing imaginable will descend on Beacon Hills like it's some kind of Sunnydale. They agree to do it anyway, which suits Dr. Deaton just fine because in addition to being a Celtic emissary and an animal doctor, he is also quite the shipper. He pairs Stiles with Lydia because he wants them to bond even more after their air-stealing kiss. He pairs Isaac with Allison because he knows Isaac and Scott are never going to make a move on each other unless they have her as a sexual buffer. And he pairs himself with Scott because there's no greater bond than revealing to a werewolf that he is Lupine Jesus.

Into the baths they go, clutching their parents' mementos — a badge, a silver bullet, and a watch — and right before they are submerged, Stiles goes, "Hey, Scott, if I don't make it on account of I'm not a wolf, just know I love you, OK? Oh, and also, your dad is back in town. You know, your dad? The FBI agent who was always giving me shit about being a smartass? Yeah, that guy. He's in Beacon Hills again."

Next week: The lunar eclipse blocks out the whole moon, but instead of taking advantage of the werewolves' powerlessness, Jennifer Blake spends the whole time shouting at Derek about how maybe he can stomach touching her again now that it's totally pitch black and he can't see how ugly she is. Deucalion tells everyone for the zillionth time what a deranged badass he is, but continues to do exactly nothing to prove what a deranged badass he is. Stiles saves everyone because he is Stiles and his face proves that God has a special interest in keeping him alive, and just when he's starting to feel awesome again about life and maybe kissing Lydia some more, his mom (#ClaudiaStilinski) shows up in Beacon Hills. Because she is drawn to the druid tree. Because she is a zombie.