Twelve-year-old Sam Hill and seventeen-year-old PJ discover a scary world of goblins under the earth after one of the creatures escapes through a tunnel in the ground, and when Sam follows it back down, PJ must go underground to rescue him.
- ISBN10 1101185139
- ISBN13 9781101185131
- Publish Date 18 February 2010 (first published 17 September 2008)
- Publish Status Active
- Publish Country US
- Imprint Puffin Books
- Format eBook
- Pages 240
- Language English