Under the wise and jovial leadership of their chairman Mister Tobias Walton and the shrewd and gallant Sundry Moss, The Moosepath League has foiled pirates and kidnappers, joined a hobo army to save a burning village, bumped into the supernatural, and even successfully treated a depressed pig.
Return now to the early days of this Portland gentleman's club as members Ephram, Eagleton, and Thump take it upon themselves to deliver a letter. It turns into a surprisingly complicated mission of befuddlement, made only worse by Mrs. Actonia Mint, whose best friends are invisible to the world and whose family is one embarrassment away from having her committed.

Meanwhile Mister Walton travels to Sundry's homestead, where folks are by turns, warm, memorable, eccentric, and irascible. The travelers deal with romantic entanglements and get wind of a ghostly visitation, even as league members climb up and down Portland's social ladder in search of the elusive Walter.