Soon-to-be fifth graders, Paul Drummond and Billy Sparks’ summer vacation at the beach with Lige Drummond, Paul’s grandfather, is interrupted when Lige’s best friend Jess Hubbard disappears, and the boys are off to find him in Shumbus, a strange land deep within the Earth.

Billy paused but then slid into the dark space with Paul close behind.

Billy waited for Paul to come up next to him, and they crawled toward the far corner.

“Yuck. Feel how muddy this place is,” said Paul. “Mr. Hubbard had to be down here to get as muddy as you said.”

Billy preferred looking for spiders and rats to answering his friend.

“Shine the light over here, Billy. Stop looking for the . . . the other stuff.”

Billy aimed the flashlight into the corner.

“Yeow!” both boys cried.

The circle of yellow light fell upon a large round hole in the mud. Both boys crawled through the slimy mud to the hole’s edge and peeked into it. Billy stretched the flashlight as far down the hole as his arm reached.

“I can’t see the bottom,” he said.

“That’s ’cause the hole curves. Give me the light,” said Paul

Billy handed the light to Paul, who reached as far down the hole with it as he could. Left in the dark, Billy nervously inched closer to Paul and the dimly lit hole.

“Hey!” Paul exclaimed when Billy bumped into him, and he felt himself sliding in the slippery mud at the edge of the hole. He grabbed Billy to keep from falling into the hole, but this only pulled Billy along with him.

“Let go of me,” Billy pleaded. “We’re slipping down!”

“I’m falling!” screamed Paul.

“We’re going down,” Billy cried. “Look out. Here we go!”