It is the last day of the school year. ANDY WALTON, 15, freshman, a poor city kid, watches with jealous eyes as the popular kids leave school to kick off the summer in style. Andy ditches his adoring, 11 year old puppy of a brother, MARK WALTON, to tag along with the popular kids, specifically CLAIRE BROMAN, 15, a beautiful but aloof blonde, and Andy’s secret crush. Desperate to impress, Andy steals some celebration booze from the local grocery store where his Mom, SALLY WALTON, 48, works. But before they make it out of the grocery story parking lot, the store security guards tackle Andy – all in full view of Claire and the rest of his ‘friends’. The store manager agrees not to press charges, but Sally’s job is in danger; this is the third time this has happened. Furious and fed up, Andy’s father JIM WALTON, 55, tells him he’ll spend the summer working off the debt at his Uncle’s store on Walton Island.
Deeply resentful of the entire situation, Andy leaves the city for the first time, accompanied by his irritatingly adoring little brother. Crossing miles of foggy sea, they arrive at the island and are greeted by their estranged uncle, TRENT WALTON, 58, the black sheep of the family. As they settle in for their first night on the island, the boys learn that this won’t be their first summer on the island – it will be their last. Trent is selling off the last piece of the island, and their family’s legacy is about to be wiped away forever. Feeling a little drunk, a little sentimental, and more than a little reckless, Trent opens up, revealing a family secret. A secret about their eccentric grandfather who disappeared 40 years earlier . . . taking with him the source and location of his vast fortune.
For the first time in his life, Andy sees a way out. A way to escape poverty, live the life he’s always wanted, and break free from the family that doesn’t seem to care. All he needs is his grandfather’s money. But where to start? Andy has one clue – an engraved gold pocketwatch, swiped from his Dad’s dresser, the only heirloom left behind by their kooky grandfather. As they search, they begin to unravel the many secrets and mysteries of the island. They are told ghost stories about the North Forest, a dangerous and uninhabited part of the island. They discover that their grandfather was an odd genius, a legendary man who built up the entire island before his mysterious disappearance. Along the way, Andy is shocked when he encounters Claire, his crush from school, spending the summer on the island as well. As it turns out, she is the daughter of the island’s richest and most powerful man, JOHN BROMAN, 70, rich, charismatic, everything Andy wants to be. Claire and Andy find themselves both attracted and irritated by each other. With each passing encounter, they discover that the mystery surrounding Andy’s family is inextricably woven together with Claire’s father’s shady past.
The search becomes more exciting as one clue leads to another…a burned clock tower…a lighthouse…a WWII decoding machine…and Trent’s very own solid gold pocketwatch. It becomes clear that their grandfather had a plan after all, a plan to leave his fortune for his sons and heal their fractured relationship. But the boys aren’t the only ones looking for their grandfather’s lost fortune. Sinister forces threaten at every turn, and will stop at nothing to keep the boys from their quest. After staging a heist at the Broman mansion, the final clue directs Andy and Mark deep into the North Forest, where for years people have gone in and never come out. Their mission nearly complete, the boys are captured by the man behind it all – John Broman. Left for dead in an empty underground tunnel, Andy realizes the destructive nature of his own greed for the first time, and is comforted by the one person who never deserted him, his brother, Mark.
Working together to find a way out, the boys discover a passageway within the tunnel, a passage that leads to an underground grotto, a passage that reveals the last thing they expected to find: a gold mine, the source of their grandfather’s fortune. But in the moment of their discovery, Broman and his men appear. Broman has also been searching. It is the answer to all his problems, and the boys led him straight to it. Andy puts it all together – Broman killed their grandfather, Broman cheated Trent out of their family’s estate, Broman was behind the Walton family’s poverty and disconnection. As Broman and his men collect all the gold they can carry, the mine begins to collapse. Andy and Mark leap into the churning water of the grotto, and Andy swims them safely out to sea.
Rescued by their Uncle Trent, and father, Jim, the family is re-united. Police swarm the island, and take Broman into custody. The boys show their father the gold nugget they managed to keep, but realize the summer has brought them something far more valuable than any riches. The mystery has been solved. The family is whole again.