The lacrosse party is JUMPING, but the big problem is that Liam threw his own party and now the older jock with the original party is super pissed. Luckily they have hundreds of dollars to pay him off. This is a horrible idea for a number of ideas, and at the top of the list is throwing it at Scott’s house while his mother is working the night shift.
Liam and Hayden take a break from their watch=over of Gwen to make out, which is interrupted by Gwen taking off. Corey is trying to have a good time, but he thinks they forgot something. He also doesn’t think he’ll be able to fight well if the Riders show up. But Mason is not about to let his boyfriend feel bad about himself, and they dance to loosen up a little.
Gwen is upstairs alone, reminiscing over her missing sister, when a Rider shows up. Looks like they DID forget something: spreading mountain ash on the upstairs windows. Gwen is in a panic, but no one else can see the Rider. Corey goes chameleon to get a line on him, and as the Rider goes by, touches him. This brings the Rider into the visible world, and makes the whole situation messier.
The older kids are still talking with Grampa, trying to convince him what year it really is. Malia also has a horrible idea: Scott using his claws on Grampa, which would probably kill him. Talking starts to get even more difficult once the sun goes down, and Grampa gets even more upset. Somehow, Lydia manages to calm him down with intense math equations. It works, but he then reverts to a different time.
Grampa has a moment of lucidity, and knows all of them based on all their parents. And he’s kind of a douche. The Sheriff shows up and puts the kabash to all of it. But as he’s leaving with the kids, Grampa Jerk yells at him to go back to his dead wife and loser son, which strikes a cord with this alternate timeline Sheriff who has an alive wife and zero sons. Looks like the Riders left a loose end.