Scorch Trials (Maze Runner Series) -- Paperback / softback

Thomas was sure that escape from the maze meant he would get his
life back. But no one knew what sort of life they were going back
to. The earth is a wasteland with people driven mad by an infection
known as the Flare. Instead of freedom, Thomas must face another
trial. He must cross the Scorch to once again save himself and
his friends.