Scott must prevent a potential disaster while Lydia and Allison find an unlikely teacher. 

A bunch of men are looking at a wolf lying still on a pillow while waiting for Dr. Deaton to arrive. 

Deaton asks if Yuki has consumed any lichen and needs a sample to treat the wolf. The men are afraid to go to the lichen. It appears to be the same spot where Argent defeated the Nogitsune years earlier.

Deaton is there to get the lichen that was grown from the Nogitsune because it has the power to kill the fox hiding inside of Stiles.

The electrical wire falls and a driver breaks a hydrant spilling water. People step into the water, getting electrocuted. Isaac among them. Kira springs into action, grabs the line and absorbs the electricity. Her mother looks on.

Stiles is missing for 48 hours and Isaac is hospitalized. Stiles sends a text message to his father.

Allison hasn't been able to see Isaac because she's not family, but he doesn't have any family. Melissa lets her and Scott into the room.

Scott knows Isaac is in pain when he touches him. He tries to take some away with his touch.

Stiles is in the basement of the school and the twins and Scott find him. He knows he's been doing things, but he doesn't know what, why or how.

The cross country team is about to head out on a trail covered in steel traps.

Derek breaks into Argent's apartment with an emitter asking why it was in his loft. They both admit to spending the last two days looking for Stiles. 

Stiles drives to Coach.

Argent finds money in his bow case and Agent McCall shows up with Silverfinger's silver finger.

Stiles finds a length of chain on the course and pulls it and Coach is struck through the chest with a bow.

Lydia and Allison go to see why Peter is looking for Lydia.

Peter tells Lydia he's the one who brought out her power and that the scream isn't the power. It just drowns out the sound so she can focus her hearing. Peter can help her learn to focus.

Mr. Yukimura finds a boy on a bus with a present wrapped like coaches. It's a bomb.

Talia stole a memory from Peter and he wants to get it back with Lydia's help.

Lydia hears what Talia's claws were hiding. Peter isn't just an uncle.

Kira's parents are sacrificing "tails" to bring forth Oni. Stronger ones.

There is a bomb, but not at the school. It's in packages that were delivered to Sheriff Stilinski.

Malia is Peter's daughter.

A fight breaks out between the Oni, Stiles, Scott and Kira. Scott receives a full sword into the gut and then the Nogitsune returns twist it inside of Scott.

The more pain and strife Scott took the more Stiles wanted it. That was the setup.

Deaton arrives with the serum and removes the sword from Scott. He's poisoned the fox, but it's not dead yet.