The first novel-length story from Harmony Boom Island. The Adventure of the Mysterious Adventure follows four friends on their first trip on their tugboat, trawling through the high seas in search of adventure, mystery, and adventurous mysteries. Harmony Boom Island is a giant humongous ancient creature who lives in the ocean. It is so big that its back is an entire island, complete with trees and houses and castles and stuff. It swims around the world and nobody knows where it came from or what it's doing. It has been swimming around for at least thousands of years, and probably much longer. Several years ago, renowned mad scientist Dr. Lara Jagwit disappeared along with all of her research into creating monsters, plus a bunch of self-aware robots, called Robubs. It turns out that she and the Robubs had moved to Harmony Boom Island, where she continued her research and eventually created different species of creatures to live on the island. Those species are Klugs, Mormoes, Gooliebirds, and Mazzlebugs. Sometimes they have adventures.