Mildew used these boots to create false Hideous Zippleback footprints in the snow leading to the Academy, where Barf and Belch were sound asleep. He then stole the villagers' boots, took chunks out of them, and piled them up in front of the Zippleback to make the villagers believe that it had stolen the boots. While the villagers did believe Mildew, Hiccup noticed that the footprints were much too shallow to have been made by the full weight of a Zippleback. Unfortunately, no one else was aware of this, so the villagers proceeded to blame the dragon. Fortunatly, Gobber promised to fix the villagers' boots by the end of the day.
Later, after Mildew's meadilng caused the dragons to be bannished from Berk, Hiccup discovered the boots and a Monstrous Nightmare Claw Stick behind a curtain in Mildew's house while he was fixing Mildew's damaged roof. However, Mildew and Fungus returned before Hiccup could take the evidence and disposed of the two items by throwing them into the ocean.
Hiccup mentions the boots when he and the other Dragon Riders are looking for them after Mildew threw them and the Monstrous Nightmare Claw Stick into the ocean. Fishlegs states that, as the ocean is so vast, it would be extremely unlikely that the riders would find anything. Hiccup later brings up the boots to Stoick, who requests to see them. Once Hiccup tells him that Mildew threw them into the ocean, Stoick claims that Hiccup would require more evidence to accuse Mildew of high treason.