In the summer of 1896 in Portland, Maine, several people are embarking on adventures of a most audacious and entertaining nature. Cordelia Underwood finds, in the newly discovered sea chest of her late uncle, the deed to a large parcel of land.

Cordelia and her family soon suspect that a mystery surrounds her land, that something on it might hold the key to a secret two centuries old. The large-hearted and wise Mister Walton, who never hears of an excursion he isn't eager to join, finds he attracts a trio of hapless friends, the exuberant founders of the Moosepath League.

As these memorable and appealing characters wend their way up the coast of Maine into the northern wilds, they encounter old salts and bootleggers, tellers of tall tales, grande dames, and prospective beaus. They witness apparitions, meet opinionated relatives, search for Maude, the fugitive bear - and, of course, espy the moose that puts the moose in the Moosepath League.