Lost Underground is a story about school children who go on a trip to some caves.These caves were very large and people could go into them only with a guide.However,four children decided to explore on their own.They went in the caves with a group,but left the group and walked down a tunnel.they thought it would be fun to explore the caves alone.Soon they came to a hole in the wall.they climbed through the hole into another part of the cave.Then they decided to turn back but they could not find the way.they were lost in the caves.When the guide led the other children out of the caves,he counted them.he discovered that there were four children missing.He had to go back into the caves to try to find the missing children.