Sixth grade takes a turn for the weird when Hector Griggs discovers he has the ability to turn invisible. Sure, ever since Hector's former best friend Blake started bullying him, he's been feeling like he just wants to disappear...but he never thought he actually would. And then, Hector meets another invisible boy, Orson Wellington, who has an ominous warning: "I'm stuck here. Stuck like this. It's been years. The gelim's hunting me and it'll get you, too."

It turns out, there is more than meets the eye at St. Lawrence's Catholic School for Boys, and if Hector is going to save Orson--and himself--from the terrifying creature preying on students' loneliness and fear, he'll need to look deeper. With the help of a mysterious new classmate, Sam, can Hector unravel the mysteries haunting his school, and discover that sometimes it takes disappearing to really be seen?