Xena and Xander Holmes, an American brother and sister spending a year in England, use clues in their ancestor Sherlock Holmes' casebook as they try to solve the mystery of a monster threatening a peaceful country village where a documentary film is being made.

As a documentary is filmed at their middle school, roles reverse for worrier Trevor and his lifelong best friend Libby, who has always rescued him from embarrassing situations but is now focused on being "cool" and no longer wants to be his "friend friend."

The school year is almost over and it is time for Westside Middle School's annual camping trip, something that Trevor Jones would desperately like to get out of as he is terrified at the prospect of coyotes, bears, dining halls, and eighth graders--and his cabin is supposed to be haunted.