Summary of the book Beware: spolier alert!!

The book is about a boy that has a friend named Chip. He lives with his family and everything is fine, until. They get strange letters saying," You are one of the missing." Then, they find out that Chip is adopted also. The look through Chips private documents. They find a post-it note it had a name on it. The call it and a FBI agent answers. Then later they get another letter this one says," Beware they are coming back to get you." Then Jonah gets a call, his dad has made an appointment to meet someone. They go to meet the person and its the same guy that answered the phone when Chip called. Jonah later goes to the bathroom, and someone tells him to check out a file on Mr. Reardons desk. Jonahs sister takes photos of the file while Jonah creates a distraction. Later on, they look at the file on Chips computer. It said,"Survivors." At the bottom of the page there was two names. Chip Winson and Jonah Skidmore. Then if that isn't enough, he see's someone in his room. The person had move his letter that said "Beware." They then called a survivor and they were moving. Everyone on that list was in close towns near Jonahs. They call people on the file under, " Witnesses." They won't talk about the situation. Then, someone wrote a letter that said," Meet me at the library to talk." Later, they meet the lady and she talked about the situation with the FBI. The woman walked away, then vanished. They then think there crazy because people can't just vanish. The woman thinks the plane is a time machine that brought them to the future. Then they go home and Chip calls. He said the file pictures vanished. There not there now! They go to the basement and talk about what Angela said. They list what they know. They try to call JB, the phone is disconnected! He trys to write a letter to her, but he thinks what if someone else sees the letter? So he throwed the letter away. They visit the house the are supost to move in to and the neighbor says no one lives there. She said I don't know anything about that and you shouldn't eather! They get a flyer that said," Adoptees on the Cusp of there teen years.....a conference for Adolescents and Their Parents. Is it a trap? They decide to go to the confrence. They arrive and sign in. They find someone that was on the list. They take a hike with all the other kids. They are lead in to a cave. The leader has a hand scanner. He was making everyone touch the rock formation. The rock door shut behind them. They are fighting Gary, when they heard gunshots. The kids find out their from the past. Then, Angela arrives and points a gun at the enemys. The gun tha Gary had was not a gun. It was a educidator. JB is an enemy and wants to hurt them. They tie them up and try to escape. They find out that they were put on the plane by these people. They are sending them back in time, where they belong. They get sent back in time and have to fix the fifteenth century. As they landed a voice came over the educidator and said," Welcome to the fiteenth century. Good Luck."