Invisible by Pete Hautman

Doug isn't a school athlete or a popular student. He doesn't go out for theater. And he spends a lot of time working on his model railroad. Andy is a popular student, a great athlete and involved with school theater. The two aren't what you would expect for best friends. But they live next door to each other and have been best friends forever. Late at night, they talk to each other through their windows. But things are just not right somehow. As the days go by, we learn what it is.