It’s a busy night at the hospital. Mrs. McCall has to wheel patients with bloody stomach wounds around and try to find an MIA doctor. When Scott comes bearing takeout, the harried nurse decides to take a break. A woman comes to Mrs. McCall begging for pain meds and is refused. Scott sits next to the ailing woman and tells her human contact can help. Don’t hit on her right now, dude! Just kidding. He’s using his werewolf power to take away her pain. That’s when Ethan walks in with a pallid, gasping Danny.

Poor guy needs a doctor — too bad Beacon Hills’ only available one is stuck in traffic.

Scott immediately accuses Ethan of hurting Danny. Chest pains and trouble breathing aren’t really a werewolf’s MO, though. Then we get a far-too gratuitous shot of Danny’s mistletoe-filled vomit.

The doc is still stuck in traffic, but a moth has joined her in the car. Then a bunch more rush in. This can’t be good. We’ve seen The Mothman Prophecies!

All the nurses and doctors are preoccupied, with or without moths, so Mrs. McCall has to treat Danny’s collapsed lung in a badass fashion. Scott’s impressed by his mom’s nursing skills.

Scott accuses Ethan of going after Danny, which the werewolf denies. Instead, he explains why he took a fancy to Danny and Aiden started hooking up with Lydia: “We knew one of them was going to be important to you, and now we know it’s Lydia.”

The doc’s empty car rolls by, distracting the werewolves. Empty... except for a moth.

There have been two separate kidnappings, Sheriff Stilinski helpfully explains when he arrives on the scene. Both victims are doctors. Away from the grownups, Scott and Stiles figure out that the missing doctors are part of the sacrifice: They’re healers. However, Danny doesn’t fit the profile. A message comes over the police scanner, saying a body’s been found.  

It’s a who’s who of onlookers at the dead body crime scene: Deucalion, Ethan, and Mr. Argent are all there.

After Derek’s red-light alarm goes off, Cora notices a symbol on his window. It means they are coming, Derek tells her. Tonight. It’s nice that you gave a warning, Alpha pack, but it’s a bit short notice!

Mrs. McCall’s awakens to find Isaac and Scott passed out in her room. Isaac tells his surrogate mama they were watching over her, and it’s less creepy than it sounds. They just don’t want her to be the third sacrifice. Whatever, says the tracheotomy-giver. Go to school.

Clearly, Ms. Blake’s time with Derek has rubbed off on her, because she thinks Mr. Harris’s disappearance is sketchy. Instead of paying attention, Scott and Stiles are discussing how the dead doctor died of asphyxiation not strangling.

Luckily, Beacon HIlls High School’s cell phone policy is lax. Deaton calls Scott to tell him, “You’re my only hope … I’m going to be taken. I need you to find me.” Deaton, who’s been holding a moth the whole time, hangs up without giving any more clues. Good luck, Scott! A swarm of moths flutter their wings menacingly against Deaton’s window.

Boyd and Isaac fake sick to protect Derek from the Alphas. “I’m in trouble, then,” says their surly leader. He spoke too soon: Boyd has a plan. Using Gerard’s method of subduing werewolves with electricity, he hopes to take down the Alphas.

Deaton is gone, though Scott ran to the vet's office as fast as his werewolf legs would carry him. (Or he drove.) Sheriff Stilinski is on the case. “I need you to tell me everything,” says Stiles's dad. Um, how much time do you have, officer?

Boyd says a bunch of stuff we don't understand then makes an electricity pun.

Back at Deaton's, Scott argues with Stiles, saying the sheriff deserves to know the full truth and nothing but the truth. After all, Mrs. McCall got over it – eventually. Then Stiles delivers a moving “I can’t lose both of my parents” speech, and Scott folds like a pair of pants from Macy's, proud sponsor of Teen Wolf. Yet Stiles decides his pops would be better off knowing there are werewolves in the world, and Scott offers to help deliver the bad news. Emotional Teen Wolf moment.

It's interrupted by Ms. Morrell, who just wants to find her brother. While diverting the sheriff, she whispers a clue to Scott and Stiles: To find Deaton, they need to use the one person who has the ability to seek out the supernatural: Lydia.

Unfortunately, Lydia's making out with Aiden at the moment. The fire alarm goes off. After the werewolf bolts, Lydia heads for the door.“You don’t have very good taste in guys, do you?” says Cora, who's pulled the alarm in attempt to get Lydia alone.

TV's greatest crime-solving duo, Nurse McCall and Sheriff Stilinski, discuss ligature marks. Can we have a spin-off with them when the Teen Wolves go to college?

“Derek would like to kindly ask you to stop seeing Aiden,” Cora says, handing down the royal decree. Lydia points out that a werewolf is small potatoes compared to her history with guys. “My last boyfriend was a homicidal lizard, so I think I can handle a werewolf,” Lydia says. When Cora grabs the redhead, Stiles arrives and  tells her to let go.

As Stiles, Cora, and Lydia try a laundry list of pseudo-psychic methods to find Deaton — ouija board, psychometry, automatic writing — Scott seeks out a mysterious ticking. It’s Deucalion. The Alpha offers to help find Deaton. It turns out Deucalion is something of an expert on the druids and denies being responsible for the sacrifices. Because Kali is on her way to kill Derek, the blind werewolf tells Scott he has to decide between Derek and Deaton. Then he leaves Scott with this important clue:  Let the current guide you. OK, hippie.

Just as “OMG Lydia, what the heck kind of psychic are you?” practice threatens to get out of hand, Scott bursts in the classroom to tell her, Stiles, and Cora that Danny was a target, not a sacrifice.

The nurse and sheriff are continuing their ligature mark conversation. Mrs. McCall has a deep knowledge of ancient torture techniques and hypothesizes that Deaton is languishing in a crucifixion pose.

On his way to save Deaton, Scott makes a pitstop at Allison’s. Mr. Argent arrives unexpectedly, and Allison pulls her ex into the closet. While Mr. Argent is fondling his maps, Scott gets a little too... excited about being in the closet with Allison. She tries not to laugh over  his manhood, then they almost kiss. Finally, her dad leaves, and seven seconds in heaven is over.

The closet buddies pore over Mr. Argent’s maps, realizing that the hunter has marked off the whereabouts of all the dead bodies – even the ones that haven't been found yet. There will be 12 bodies. Scott figures one location is where Deaton is. Scott sneaks out.

Credit: MTV

As ‘60s spy music plays, Stiles goes into Danny’s hospital room and roots around for clues. A slightly drugged Danny wakes and is  skeptical when Stiles tells him it’s all a dream. A thorough search of Danny’s backpack turns up a paper. Danny’s been working on a project for Mr. Harris on currents.

Isaac, Boyd, and Derek are powerless. Literally. The Alphas have cut the power, meaning their trap will fail. Derek’s still ready to battle.

The werewolves are knee-deep in the water they prepped for Kali’s electrocution. The female Alpha shows up and mocks Derek for hiding behind teenagers. Then she shows off her secret weapon: a captive Ms. Blake. Kali wants to go one on one. “I’m gonna rip your throat out — with my teeth,” snarls Derek. Now that’s love!

Based on complex calculations and Danny’s homework, Cora figures out Deaton is at the vault. They really should’ve just tried Beacon Hills’ No. 1 spot for kidnappings first.

Boyd texts Cora to alert her to the failed plan. “I can save Deaton myself,” Scott says, telling the others to help Derek.

Montage: Kali and Derek fight, as Lydia, Cora, and Stiles head to the loft to help.

Scott runs into vault. The ring of Mountain ash throws him back. Deaton hangs, looking close to death. Trapped by ash, Scott pushes against the glowing forcefield.

Meanwhile, Kali and Derek continue to slosh around in the water, trading blows.

Deaton looks at Scott, who’s straining against the sci-fi-looking shield. Suddenly, the werewolf’s eyes glow red. Just after Scott is knocked back, Stilinski arrives to shoot down Deaton.

Cora, Stiles, and Lydia restore power to Derek’s apartment, knocking out several of the werewolves.

In the aftermath, Kali wounds Boyd. She tells Derek he has until the next full moon to decide to join the Alphas or she’s killing everyone.

A teary Derek tries to stop Boyd’s bleeding. “It’s OK,” says Boyd. Derek says he’s sorry. That doesn’t seem to like apology enough, but Boyd says it was worth it before dying.

Accessing Boyd’s memories, Derek sees Erica. She’s asking about lunar eclipse. “They last for hours, you know.  wonder what will happen to us. Maybe it will make us stronger. I hope it’ll make us stronger,” says the deceased blond werewolf.

Allison visits her grandfather Gerard. “Surprised to see me?” asks the hunter. He’s only surprised it’s taken her so long. (Not everyone has Papa Argent’s maps, Gerard.)

It turns out the sheriff found Deaton using old fashioned detective work and his noggin. He recognized a Celtic symbol in the vet’s files. Um, that’s lucky.

More importantly, Deaton has some info about Scott’s red eyes. It’s rare, the vet tells him, but sometimes a Beta can become “a True Alpha” through strength of character and sheer force of will. “You knew this would happen,” Scott says to his mentor. “I believed,” Deaton corrects him. But Scott needs to watch his back. Deucalion is after him.

Next week, we see a Derek in flashbacks, when his life was basically a Twilight novel.