When Miss Pimm, Enchantress of the Marsh, decides to retire, she enlists young Hilary Westfield to gather a band of scallywags and prepare to challenge Captain Blacktooth in an all-out battle for the presidency of the League in order to save the kingdom.

Toby enters a contest that will determine the world's greatest detective and teams up with amateur sleuth Ivy to solve the mystery, but the pretend murder turns into a real one, and all of the participants become suspects.