Johnny Bey's older brother is missing. His family is suffering, and Johnny can't make things any better.

Then one day he stumbles on his brother Brendan in an abandoned quarry near their house. Brendan is still 13 years old, the same age he was when he went missing. He's also see-through. Transparent. But Brendan denies he's a ghost, and invites Johnny to go with him to the magical world of Mizzenglass, where missing children go.

After braving a dark and perilous cave, Johnny emerges with Brendan into a magical world. There, a beautiful Gatekeeper guards a land of children who play away their days. But Johnny wants to take Brendan home. The Gatekeeper tells him he can try, but that it isn't easy. To get Brendan out of Mizzenglass, Johnny has to play a dangerous game against the evil Shadow.

Johnny and Brendan form a Company of Seven with five other missing kids who want to go back to their families. Chief among them is Claire, who isn't sure she wants to face all her problems back in the real world. But Claire knows she can help the Company win the game, and reluctantly joins them in battling the Shadow through worlds of increasing peril. In this book for children ten and up, Johnny and his friends fight through a mysterious water world, a land of extinct animals brought to life, and most dangerous of all, an Ice Ago world of hunters.

Johnny Bey is a special kid, and he has magic on his side. But trying to grow up is hard, especially with a troubled friend like Claire and a brother like Brendan who refuses to play by the rules, even when it means going home.