1) There is an inexplicable mountain that only Moss can see located at a corner in her small town.
2) Moss is reluctant to go to the vet clinic located at the base of the mountain due to her unease with its presence. She sends her brother Charlie instead with their cat Nubs.
3) Two weeks later, Nubs is accidentally hit by a car. This prompts their mother to demand a new kitten, increasing the pressure on Moss and Charlie to confront the mountain.