The Bobbsey Twins: The Big River Mystery — Laura Lee Hope

A Two-weeks' visit with Aunt Alice on her private island in the Hudson River is an exciting prospect for the Bobbsey twins. The more exciting because Bert, Nan, Freddie, and Flossie know that Aunt Alice plans to give each of them a special present - just because she loves them.

But the twins naturally seem to attract adventure. Imagine their surprise when they learn that the U.S. Customs Service has its eye on the island. Puzzling, too, is the disappearance of a big wooden crate containing their great-great-aunt's valuable heirlooms.

The twins don't spend all their time investigating clues. There's too much to do - with a whole island, a bost, a historic river, and a new "treasure" at every turn.

A night's camp-out unravels one puzzling mystery, but it takes a trip all the way down the Hudson to New York City to solve the other. And the third mystery - why Aunt Alice doesn't give them their presents - they're too polite to ask, of course - has a happy ending too!