With Samantha's little brother Joshua along, the girls didn't think they'd get to go on an adventure this summer. They could not have been more wrong.

Josh disappears mysteriously into the cornfield while on his pony ride. Marcus, happy to finally be allowed to reveal himself to Val and Sam, informs them that Josh has been taken to another realm. It's now up to them to find a treasure in exchange for his safe return home.

With help from a new friend, they follow secret caves and tunnels, and even discover the city of gold. But they learn that is not the greatest treasure of all.