Last stop

"Watchers have power. They can see things that other people can't. Like David Moore, who glimpses his father in the phantom subway station of another world. Possessing the seeing powers of the Watchers, David Moore glimpses his father in the phantom subway station of another world, a situation that poses a surprising twist."@en
"It's been six months since David Moore's father disappeared. After months of strange behavior--baby talk, forgetfulness--he simply vanished forever. The Public Guardians searched Franklin City, but they couldn't turn up a single clue. David is beginning to give up hope when his subrail train stops between stations at the abandoned Granite Street platform. On the other side of the glass he sees a crowd of people. In the middle is his father, waving. When a psychic suggests that David may have the power to see into another dimension, he and his friends scour the city in search of a portal to the other side. To learn if his father is alive or dead, David will need to discover the secrets of the abandoned station."@en