Amidst the ambition and competition at the elite Morton Academy, Liz, Taylor, Kat, Marcus, and Cole join forces to investigate a string of mysterious deaths and race to uncover the truth before more of the school's best and brightest fall victim.

Told in text messages, middle-schooler Ava is having a really bad day: her parents are getting divorced, she has had a big argument with her best friends, and the charge on her cellphone is getting low; but things are about to get a lot worse because the lockdown alarm has just gone off, and there is an intruder in the school building.