Lost Key Mystery/Door Knocker Mystery

Forgetful Mayor Fox has misplaced the giant key to the city that he's supposed to be presenting to a visiting astronaut. Huckle and his pals try to figure out where he set it down. They learn that Mayor Fox did one thing while touring a candy factory that required both his hands - stirring a huge pot of candy goo. Not far away they find a big chocolate-covered key. A couple of Busytown residents are confounded by mysterious knocking at their doors. Huckle and his mystery-solving team attempt to find out who it is, but they're eluded at every turn. When they're drawn to a knocking sound in a treetop, the kids discover a noisy woodpecker. In the end, they learn it's that same bird responsible for all the door knocking.