Mr. Baker's 8th grade class is headed to Carlsbad Caverns for a field trip. Some of the students are more enthusiastic than others about the trip. Eric isn't thrilled that his mom is the chaperone. Silvia has panic attacks and is worried about one coming on when they are underground. They are exploring deep in the cave system when an earthquake hits. Mr. Baker is swept away and the rest of the class falls into an underground river. Eric is able to get to shore, but the rest end up at a huge lake. As they try to find each other and the way out, they discover they are not alone. 

Carlos is the young king of Medianoche and his struggling to live up to his father's teachings. The people of Medianoche have lived underground for four generations. Their enemies, the Worms, led by Jana, have increased their attacks and tensions are high. The arrival of surface dwellers has thrown everyone into a tizzy. When Carlos meets up with the survivors he has to make a choice. 

This was an excellent adventure. It was fast-paced and exciting and I didn't want to put it down. I wasn't sure how I was going to feel about the Medianoche storyline, but it worked. Eric was wonderfully resourceful and I enjoyed the fact that he learned the difference between being alone and being lonely. Silvia's story was perhaps my favorite. She was the true hero of this story. In fact she saved the lives of two of her classmates. She became the leader of the group even though she was terrified.