Ember Boys. Flint and Tinder, #1

Emmett Bradley thinks his adventures are over. Together with his friends, he stopped an ancient evil and lived to tell about it. But life as a survivor, even as a survivor of a victory, isn't easy, and when Emmett runs away from Vehpese, Wyoming, he takes a few things with him: a battered ego, a broken heart, and his addictions. He's lucky that Jim Spencer, his former English teacher, happens to have ended up in the same small, coastal town.
He's even luckier that Jim is doing everything he can to help Emmett hold himself together. When Emmett's parents commit him to the psychiatric ward of an infamous hospital, though, Emmett finds himself struggling day to day to remember that the life he's lived-a life with monsters and psychics-is real. Every day, he finds himself a little less certain that he can trust any of his memories. A chance encounter with a strange girl, though, forces Emmett to confront the possibility that things around him aren't quite what they seem.
The hospital may not actually be a hospital. His adventures may not be over. And the ancient evil he stopped in Wyoming might have been only one strand in a larger web. Then Emmett is attacked by a dead man, and he realizes that he's caught up in a war he doesn't understand. He must hurry to learn the truth about what's going on, and he'll need Jim's help to do it. He just has to convince his old teacher that things between them aren't too complicated already-but first, Emmett will have to convince himself.