Learning to become a witch is hella difficult! Luckily, Gwen can always count on her two best friends in the whole world for help. Except Sloane and Miles aren't exactly from this world. They're from the Hallowlands, a monstrous realm, which they can only leave as the year creeps toward Halloween. This year, Gwen is determined to flex her magical skills. Armed with her first-ever grimoire, she's hoping her friends will finally see that she has what it takes to leave boring suburbia behind and join them in the Hallowlands.

Except Gwen hadn't counted on Hiro, a local kid obsessed with hunting the supernatural. When he and his reluctant sidekick start making trouble for them, the monster squad will have to fight to avoid having their secrets exposed--or worse. But when Gwen's quest to prove herself leads to a string of unintended consequences, the five of them may just have to band together to take on something even more nightmarish than being a teen.