The film will take place one year after the events of Dog Days, Greg Heffley and his brother, Rodrick convince their family to go on a road trip for their grandmother's 90th birthday, but they actually intend on attending a video game convention.
After losing her memory, Jane visits her childhood home at the suggestion of her psychiatrist. It is the home where the rest of her family was massacred. She begins to see unexplained things and strange clues within her photos that suggest she may be responsible.
A teenage girl (Amandla Stenberg) is unable to leave her home because she has an immunodeficiency that makes her allergic to almost everything. However, her life changes for the better when she begins to communicate with the boy next door (Nick Robinson).
Roman is a man who lost his wife and child in a plane crash. The tragedy happened while air traffic controller Jake Bonanos was on duty. Roman blames the air traffic controller and cannot let it go. He is demanding answers in person.