Oto is trying to build a working model of a tank, from designs by Leonardo DaVinci. But the tank won't roll! He followed the plans exactly, so why won't Oto's tank work? Anabella suggests they ask a friend of hers for help, so they visit Florence, Italy - where Oto joins a secret society for fans of the renaissance genius! Oto figures out why his hero's plans don't work - by relying on his own logic and creativity. Meanwhile Gabi and Fico fill in for their new Italian friend, by running his pizzeria while he helps Oto.
When Mundi is startled by a Fico prank, she insists she isn't afraid of ghosts. They don't even exist! Oto and Anabella disagree - they definitely believe in ghosts. Doki wonders - do ghosts really exist? Mundi vows to prove they don't, with a trip to a so-called 'ghost town' in Tombstone, Arizona, U.S.A. As they explore the old mining town, they encounter plenty of unusual happenings but some are merely pranks by Fico, and ALL have logical explanations. In the end, they realize a 'ghost' town isn't full of ghosts - and that Fico isn't quite as fearless as he claims!