A transfixing morality tale cleverly turned on its head, "Lurker" opens with an overture: its protagonist, Matthew (Théodore Pellerin), goofing around for a camcorder wielded by a friend.

The name "blue lurker" might sound like a villainous character from a superhero movie. But it is a rare class of star that NASA's Hubble Space Telescope explored by looking deeply into the open ...