Hidden Warrior - Percy Jackson
Percy Jackson is happy. He has nothing to worry about. No more war, sadness or pressure. He and Annabeth are perfect. All his friendships have grown greatly and made him protective. One night he and Annabeth fall asleep on the beach happy, content, perfect. When she wakes up he's not there anymore. Over a small period of time some of his close friends disappear. Thalia from the hunters, Nico, Will, Chris, Clarisse, the Stolls, Katie Gardener, and lastly Annabeth. A few days later they get a letter from camp Jupiter saying that Reyna left also. The campers go into shock of how all the veteran campers go poof. They assume them dead.
A new threat comes to the camp and they have no hope of winning without the heroes. So a mysterious us force sends nineteen people to help. Wind, Death, Summer, War, Trick and Prank, Spring, Fall, Winter, Woods, Heart, Bomb, Luna, Mechanic, Dolphin, Pain, Hearth, Knife, and Storm. They all seem resentful to camp and the campers, some a lot more than others