The episode begins with Jackson Whittemore rising out of a lake at night with his wolf bite showing on an almost full moon.

 

The scene shifts to Scott McCall running through the woods on all fours. There is a flashback to him and Allison Argent making out in a car before her dad appears and forces Scott out of the vehicle before putting him at gunpoint. Allison begs her father to let him go, and he agrees as long as she swears to never see him again. The flashback ends and Scott is continuing to run before rolling through Allison’s window. Scott asks her how long they have, insinuating that they are meeting in secret, and they begin kissing.

 

The next scene begins with Stiles Stilinski asleep in the hospital waiting room. Lydia Martin wakes up in her room and goes to take a shower, making a scathing remark toward her dad on the way. 

 

Scott and Allison have now moved to the bed, still kissing and partially dressed. They manage to knock over one of Allison’s lamps and fall off the bed before Scott realizes that Allison’s parents are home early and runs out of the window. Allison’s mom walks in to see Allison on her bed, re-clothed and reading a textbook. She’s obviously suspicious and looks in the closet and outside the window, but Scott goes around to the other side of the house so that she can’t see him from inside.

 

In the shower, we see Lydia’s wolf bite. Her eyes are closed, and filthy brown water begins to rise from the drain, Supernatural style. Lydia finally opens her eyes after she’s startled by a loud noise (Stiles managing to knock over the vending machine) and notices the filthy water. She reaches down toward the drain and pulls out a hair ball. She begins to pull up more and more hair, much darker than hers, and panics. A bloody hand grabs onto her and she screams. Scott is shown hearing and recognizing the scream even though he is miles away, and Stiles, Lydia’s dad, and Nurse McCall all rush into the shower room to see Lydia gone, with the shower still running and back to it’s normal color. Stiles notices that the window is open, showing the nearly full moon.

 

Sheriff Stilinski is called in, and Stiles rattles off details about Lydia’s personal appearance to help the police find her. Sheriff Stilinski tells Stiles to go home and he agrees, but he brings Lydia’s bloody hospital gown with him and gives it to Scott, thinking that he could track her by scent. They are about to leave when Allison arrives telling them that her dad and three other hunters just left the house, and that they need to find Lydia before the hunters do.

 

The scene cuts to a graveyard at night. A teenager is in a backhoe digging a grave next to Katherine Argent's. He appears to have a black eye, and stops momentarily to stop and feel how bad it is, wincing in pain. He hears footsteps and starts looking around. After noticing a clawed hand wrapping around a gravestone, he stops the backhoe, concerned. The backhoe is knocked over and he is pushed into the grave, with the backhoe falling on top. An animal is seen digging up the grave of Collette S. Argent, 1932-2011, before running away. The backhoe is then lifted off the grave and he hears footsteps approaching. It’s Derek Hale, who offers help.

 

Stiles, Scott, and Allison track the scent from Lydia’s gown to the old Hale House. Stiles finds a trip wire there and triggers it, causing Scott to be lifted into the air. Scott realizes that someone is coming and sends them away. It’s Chris Argent accompanied by other hunters. Chris gives a very threatening speech about how Lydia can’t be a werewolf, makes a vague threat about cutting people in half, and leaves. Scott uses is claws to get out of the trap and the three continue toward the house.

 

The kid from the graveyard introduces himself as Isaac Lahey while being interviewed by Sheriff Stilinski about what happened the night before. His dad is with him, and he is a generally unpleasant man. Isaac sees Derek in the woods watching them, but when Sheriff Stilinski turns around to see what Isaac is looking at Derek is gone. The Sheriff asks what the graverobber took, and Isaac tells him it took Kate's liver.

 

Stiles and Scott walk into BHHS that morning talking about the dug up grave. They are under the impression that Lydia was involved. Jackson pulls up in his Porsche and makes a rude comment toward a homeless man digging through a trash can. In the lacrosse locker room, Coach Finstock is giving a questionable speech about Lydia’s disappearance, promising an automatic A to anyone who finds the “naked girl”.  Stiles and Scott try to talk to Jackson, but he doesn’t seem to be all that concerned. 

 

During a pop quiz in Chemistry, black liquid begins dripping from Jackson’s nose, freaking out his friend Danny Mahealani. He rushes to the bathroom as the liquid continues to pour out of his nose and mouth. Someone is knocking on the door to the stall, and Jackson assumes that it is Danny and tells him to go back to class. The knocking continues until the door is forced open, and it’s Derek. The liquid is no longer coming from his nose and mouth when Derek sees him, but Derek knows that something’s up and tries to get Jackson to tell him. Jackson launches into a rant about how he’s not part of Derek’s pack and never will be when Derek points out the black liquid running out of his ears. Derek explains that his body is rejecting the bite, although he doesn’t know why, and leaves, visibly disturbed.

 

At the class change, Allison goes to her locker to get ready for her aunt’s funeral. Matt Daehler compliments her dress, which she has in a dry cleaning bag, and she tells him in turn “nice camera”. Allison hears girls whispering about her and her aunt and walks away upset, but Scott pulls her into an empty classroom and encourages her.

 

Stiles sits in detention, giving the clock his very best glare. Stiles gets up to leave as soon as an hour is up, but Mr. Harris makes him stay, telling him he's made him his personal project for the rest of the semester.

 

The funeral is a media circus, with the police, including Sheriff Stilinski, having to physically hold people back and set up barriers. Matt is there and he sneaks under one to take photos of Allison when one of the attendees takes the camera from him to remove it’s SD card and destroy it. The man enters with two others behind him and we find out that he is Allison’s grandfather. Scott is watching from afar, and Stiles joins him. They are eventually caught by the Sheriff, who forces them into the back of his police car. A call comes in for a 415A, disturbance in a car, and another officer explains over the radio that an ambulance carrying a heart attack victim was hit, and something got into the back, leaving blood everywhere. The ambulance is on Route 5 and Post. The Sheriff responds that he is on the way and turns to give Scott and Stiles instructions, but both boys are gone.

 

Seemingly many hours later, Scott and Stiles are seen in the woods, close enough to the ambulance to see the destruction that they heard about over the radio. It’s now dark. Stiles tells Scott that he just needs him to find Lydia, and Scott swears that he will before running off. He hears something and goes to check it out, but it ends up being the homeless man that Jackson snapped at earlier in the episode, who is actually an omega werewolf. Scott chases him through the woods.

 

Lydia suddenly appears, naked, and Stiles is the first to spot her. Sheriff Stilinski is with Stiles at the scene of the ambulance, and gives Lydia his coat.

 

Scott is still chasing the omega when the omega is caught on a trip wire. Derek appears and hauls Scott out of sight just before Gerard, Chris, and other hunters show up. The omega explains that he was looking for an Alpha and heard that there was one in Beacon Hills. Gerard makes an example out of him to the other hunters by cutting him in half with a sword. Scott is extremely disturbed, but Derek forces him to watch and tells him that this is what hunters do and why he needs Derek, and a pack. When Scott asks what exactly they’re trying to do, Derek responds darkly that they’re “declaring war”. Chris Argent asks about the code, but Gerard replies that there is no longer a code once werewolves have killed his daughter. 

 

The episode ends with Gerard declaring an ultimatum:

 

“No code. Not anymore. From now on these things are just bodies waiting to be cut in half. Are you listening? (The scene cuts to Jackson in bed, coughing up black liquid with hundreds of tissues littered on the floor by his bed.) Because I don’t care if they’re wounded and weak. (The scene cuts to Scott holding Allison.) Or seemingly harmless, begging for their lives with the promise that they will never ever hurt anyone. (The scene cuts to Isaac walking into a dark subway tunnel where Derek is waiting.) Or some desperate, lost soul with no idea what they’re getting into. We find them. We kill them. We kill them all.”