As the headmaster credited with turning around the local school, Tom Fitzwilliam is beloved by one and all --- including Joey Mullen, his new neighbor, who quickly develops an intense infatuation with him. Joey thinks her crush is a secret, but Tom’s teenage son Freddie --- a prodigy with aspirations of becoming a spy for MI5 --- excels in observing people and has witnessed Joey behaving strangely around his father. One of Tom’s students, Jenna Tripp, also lives on the same street, and she’s not convinced that her teacher is as squeaky clean as he seems. Meanwhile, 20 years earlier, a schoolgirl writes in her diary, charting her doomed obsession with a handsome young English teacher named Mr. Fitzwilliam.