It’s the last day of school, and T.J. Detweiler has just pulled off the ultimate prank on Principal Prickly—dumping a bucket of slime from the ceiling as he walks into the classroom. The entire school erupts in laughter. Summer vacation is finally here.

But joy turns to disappointment when T.J. learns his friends are all going to different camps—Vince to sports camp, Gretchen to science camp, Mikey to family retreat, Spinelli to anger management. He’s going to be alone.

That night, while riding his bike past Third Street School, he sees strange lights. A truck rolls in, men in black suits unload equipment, and a tractor beam hums to life beneath the gym. He tries to tell his parents. They don’t believe him. The police laugh. Even Prickly refuses to listen—until he vanishes trying to enter the school.

Now, with only a cryptic note in Prickly’s abandoned pants—'Help Me!'—T.J. knows he can’t fight this alone. He needs his friends. And he’ll do whatever it takes to get them back.

The summer has just begun. And it’s already under attack.