Being almost grown-up is harder than it looks.

Max McAllister is convinced that turning ten means he's basically an adult. Grown-ups drink coffee, make responsible decisions, and never mess up... right? But from the moment he nearly chokes on his first sip of coffee to his disastrous attempt at pet-sitting a lizard, Max quickly learns that being "mature" isn't as easy as it seems.

Determined to prove himself, Max embarks on one hilariously misguided adventure after another—building a bike ramp of doom, surviving the ultimate school picture day disaster, and even entering the school talent show... without actually having a talent. Along the way, his best friends Leo and Hazel try (and fail) to keep him out of trouble, while his older sister Mia roasts him at every opportunity.

But when a backyard campout goes completely off the rails, Max starts to realize that maybe growing up isn't about acting like an adult—it's about enjoying the ride (and surviving the chaos along the way).