Who is Archibald Peabody, and why is his statue in the middle of the town square? Peabody, Wisconsin is celebrating its 100th birthday and the town can't wait to open a time capsule buried by its founder, Archibald Peabody. Nine-year-old Jimmy and his fourth-grade classmates set out on a quest to find out who Archibald Peabody was. Their search uncovers a scheme by an out-of-town real estate developer to build an elite housing development on the edge of town. This means destroying a part of the forest--right where their moose friend Mortimer lives. All seems lost until Mortimer kicks a loose brick at the base of the statue to reveal a key wrapped in a note and a mysterious map. The adventure leads the sleuths to an old rustic cabin that belongs to a hermit no one has seen in years. A story unravels involving a train heist, missing gold, and the man searching for it. With the Centennial celebration fast approaching, Mortimer and Jimmy are determined to unlock the mystery of the missing gold and save Mortimer's habitat at the same time.