Teen Wolf thought he ended the Kanima saga. He didn't. The lizard creäture is now under the control of Gerard.
Both Stiles and Scott are dealing with the aftermath of Matt's death. Stiles talks over his feelings with the school counselor. However, he's uncertain how to move forward. Although his dad got his job back, his friend Scott has become distant and Allison even more so.
Elsewhere, Derek's wolf pack falls apart. He's made mistakes with them and so his omega wolves decide to look for another pack. Only Isaac is uncertain. He discusses his decision with Scott, who declines to give him advice.
While Isaac visits the vet's office, he discovers he can take away some of the pain of a suffering dog. That information touches him in a profound way. Still, he tells Scott he's decided to leave with the other pack members. Then he warns him that Jackson intends to play in the championship Lacrosse game. Scott knows that means the Kanima has found a new master.
At home, Scott's mother refuses to talk to him now that she knows what he is. He prepares to leave for school, but when he turns around the Kanima is holding his mother with his tail around her neck. Gerard tells the boy they have to talk. Now Scott knows who the Kanima's new master is. Gerard tells Scott he will help him get Derek and his pack or his mother and other people he loves will die.
Scott suits up for the championship, but isn't allowed to play because he's failing his course work. Instead, Stiles gets tapped to play. Unfortunately, he's not very good. He keeps screwing up.
While everyone's focused on the game, Gerard speaks with Scott long distance. He again threatens to have the Kanima kill someone if the Teen Wolf doesn't do as he's told.
Derek seems disappointed when the omega wolves tell him they are leaving the pack, but he doesn't try to stop them. He's still furious when his uncle, the former alpha wolf decides to visit. The two fight at first but eventually start talking.
Unfortunately, the runaway wolves don't get very far. Allison and her father are out hunting. Allison corners Erica and shoots her full of arrows. She moves in for the kill when the other pack member steps in front of her. That makes Allison mad so she shoots arrow after arrow into the male wolf. Erica begs her to stop but she won't until her father shoots the bow out of her hand. He tells her they were to capture the wolves; not kill them. She calls Gerard to tell them of their success.
Scott wants in the Lacrosse game to defend everyone from Jackson. The coach says "no". That's when Isaac shows up and volunteers to do it for him. He also tries to get Scott into the game by eliminating the other players. Instead, the Kanima takes him down with venom.
Scott gets in momentarily. Gerard tells him if he helps get Derek and his pack, he'll let Scott have Allison. Fearing his girlfriend is in danger, he leaves the game to follow Gerard. He finds him in the locker room about to kill Isaac. But when Scott turns to face him, he's gone.
Derek's uncle tells the alpha wolf he knows how to stop the Kanima. They have to call him out by his Christian name. In other words, they must touch his heart.
Derek remarks that Jackson has no heart. His uncle reminds him that isn't true. Although he denies it, he's bonded to Lydia. Because of that, she can reach him.
Back at the game, Stiles begins playing and scoring. The team gets up by one point with seconds to go. That's when Jackson begins circling the group; readying himself for the kill. But whose life will he take?
Scott arrives as the game ends and the lights go out. He hears a scream and fears it's his mother. However, she's fine. It's Jackson who is down. Scott's mother tries to revive the boy with Lydia's help. That's when the sheriff notices something. His son, Stiles, is missing.