Clawtooth Mountain is a giant mountain range where Arlo and his family live. Near the base of the mountain is a river, which is the only way Arlo can determine where to find home if he ever gets lost. While trying to find a feral cave boy Arlo failed to kill out of reluctance, Poppa Henry and Arlo started to follow its tracks. When Arlo slips and injures himself, Poppa Henry decides to head back home. However, a giant mudslide arrives, and the two struggle to escape before they're washed away. Arlo is able to escape, but unfortunately, Poppa Henry doesn't, and he is washed away and killed.