Monty frequently bullies Caspar and torments throughout school.
The bus crash
Monty bullies Caspar in school and then boards the bus with Jerome for the class trip, during which, Caspar begins to have a seizure, which distracts Mr. Edwards, causing the bus to drive clear off a cliff.
Monty survives the crash with nothing more than a few bumps and bruises, but he blames Caspar. Later that evening, as the sun begins to set, Monty approaches Caspar by the fire, pretending to be apologetic simply to get Caspar to reveal a secret about himself. When he does, Monty blackmails Caspar for his vote in order to take leadership of their group.
The king is dead
When Caspar rescinds his vote for Monty, who has been abusing his power since the start, Monty reveals how Caspar did nothing the night of his mom's injury, which caused her to be in a wheelchair. And then when Caspar begins to climb the rocks to the top, Monty follows and tries to prevent the group from going home, but they join Caspar instead.
The group come across an abandoned food truck with snacks and drinks in the back. While the others scavenge the truck, Monty heads up front, where Alfie is attempting to get a signal on the radio, but he destroys it when the radio begins emitting an ear-piercing siren. Unlike most of the group, Monty appears reluctant to go home, which is due to his unfortunate home life.
They roam the countryside until catching a ride home from a woman named Zoe, who informs them that the planet has been invaded by aliens. She drops them off just outside the gates, where they split off into different directions, but not before Monty apologizes to Caspar for bullying him in the past.