WARNING! Contains Spoilers!
In this story, The main character will, and his father Mr. Burrows, digs tunnels in archeological sites. recently, they have found a old subway station. Will's dad though prevents will from telling anybody about this, because last time they dug out archeological sites, other person hijacked the dig and took all the glory. Will tries to be careful, but let his friend, Chester join one of his another dig. As time pass, Will finds something strange about his dad because will has spotted his father working on a dig secretly. Then, dad disappears. Will and Chester goes on the search for his dad, and finds out the dig Mr. burrows was secretly working on under the shed beside the house. Will and Chester kept going down, until they reached the underground city. They, though, were caught by people living underground, and he hears that his dad is in this underground city. Still, Will and Chester failed to find Mr. Burrows, and prepare an escape with cal, who is a citizen of underground city. When they escaped, Underground police were after them, and Will, Chester, and Cal faces the fact that Will's younger sister, Rebecca, was actually one of the police. By help of the lighting stone, Three of the boys were able to escape the police and escape to London.
The main conflict of this story was Will trying to find his dad. In this story, Will fails to find his dad and escape with him, so the main conflict were not resolved.
I enjoyed this book because the story were very organized, and there were several conflicts in this story which some were solved and some were not solved.