The pack is trapped in school overnight as The Alpha terrorizes them. They are stuck inside the chemistry lab, but there's a door to the roof. Unfortunately, it's locked.
Why is there a door to the roof in a chemistry lab? Nobody knows. Don't think. Just go with it. Scott, our hero, volunteers to retrieve the key off the dead janitor down the hall. Of course, he risks facing off with The Alpha.
Allison knows Scott is lying to her, but begs him to stay with a kiss. Despite her anger over the lies, Allison doesn't want Scott to die. Allison knew how to rise above and priortize. I miss her. Personally, I agree with her. Lydia's Molotov cocktail looks like a safe bet to me.
Scott refuses to stay or to explain why he can't. Tired of the lies, Allison breaks up with him. Ulimtately, Scott sacrifices his relationship with Allison to keep her safe. Or...he could just tell the Allison the truth. I know. I know. That's silly.