As the Whispering Pines' school year ends, Bobby Brown, almost 13, has been saving his paper route tips for one special thing, The New InterPolar Radio. Bobby is surprised when one of his customers, Mrs. Andrews, gives him a radio and their garden gnome, as partial payment for lawn care. The Andrews will be gone—long gone—leaving their home for the First Dimension, an alternative universe. And the gnome? He talks.
The idyllic hamlet is plagued by tears in the space/time continuum. Some residents move through them as a parlor game and even use them to commute to work. This game becomes serious as more tears randomly appear around town. One wrong step and you're in the First Dimension; once there, you can rarely get out.
Mr. Fowler, the local printer, helps Bobby learn to use the intricate radio. Its mutating code book frustrates Bobby almost as much as the opinionated gnome. Mrs. Johnson, a gifted psychic and clairvoyant, reads Bobby’s Tarot cards in lieu of newspaper tips, and guides him toward a summer adventure. Mr. Fowler and Betty Johnson share a secret: Mr. Fowler failed at the same adventure when he was Bobby’s age: freeing hundreds of captives trapped in the First Dimension.
When Bobby’s neighbor and school teacher, Steve Arland, goes on his annual rock-hound vacation, he recruits Bobby to take care of his dog, Misty. About the same time, the Stanley’s move into the vacated Andrews' house with their children, Ben and Melissa. Ben and Bobby are the same age and become best friends. Together they discover the First Dimension.
Bobby’s mother, Sally, and Ben’s mother, Maggie, follow the boys by becoming fast friends. At Maggie’s mistaken urging, Sally is tricked into entering the First Dimension. When Sally becomes trapped, Bobby is left alone in the world. As troubling events unravel for the pre-teen, Misty acts as Bobby’s protector, the only one Bobby can trust. Bobby and Misty travel into the First Dimension to try and save Sally.