In the buzzing city of New York, 12-year-old Gabriel Scott retreats from his parents' constant arguing into a virtual world of adventure and companionship. Unfortunately, as summer comes along, his parents ship him off to Kenton Woods to stay with grandparents he hasn't seen in years. Trapped in a world of small town life, Gabriel suddenly finds himself cut off from the only friends he ever had when he discovers that his grandparents don't even own a computer.
After sulking in the house for a few days, his grandfather drags him outside and Gabriel takes his first steps into the real world. Gathering all his courage, he talks to Liam, their neighbors' son, who hands him a small sheet of paper and asks for his help. From that day on, Gabriel follows Liam and his friends on a treasure hunt across town. With the entire school on their heels, they rush to solve riddle after riddle, slowly closing in on that which no one has ever found before. Along the way, Gabriel meets the head-butting twins Jack and Jordan, their dog Cat, the insane story-teller Eddie and Hannah, a young girl locked up in her room.
Hand in hand, they work to help Hannah escape and take her along on their adventure. Having spent her entire life cut off from the rest of the world, Gabriel finds a kindred spirit in the red-haired girl with the glowing eyes. But one day, a secret Hannah has been carefully hiding from the group rears its ugly head and threatens to shatter Gabriel's new life and the place he thought he'd finally found in the world.