The Lynden children - Genevieve, Corbin, and twins Gregorio and Kelly – were on a trip to visit their Grandma in St. Croix. After showing her the key, they’re off to the Beachcombing Club to see if the key is valuable. They end up having their picture taken for the newspaper. Soon the children learn they are in possession of a very important key!
The following evening, wealthy yet unsatisfied Jane Pelitiah finds the picture on the internet. She's sure the key is the one her ancestor 'lost' that leads to a gold mine. Jane, her husband, and her two cousins immediately head to St Croix to steal the key.
When the Lynden family chases after the Pelitiahs, the adventure takes them to the Canary Islands. There they find a floating pumice island, and a clue that leads them to India. A hurricane, a boat ride, a narrow brush with the Pelitiahs, joining up with their parents, a late night adventure in a famous American fort...the Lynden children are on a mysterious scavenger hunt trying to stay one step ahead of the greedy Peletiahs in order to find the gold that was discovered hundreds of years ago.
Who will find it first? And who will use it in the right way?