Everything changes in Year 9. It's full of hormonal 13-year-olds and is a critical academic turning point as the students choose their options for GCSE.
It's a year when Thornhill's students, hopefully, do some dramatic growing up but it's also the year with the worst behaviour record in the school.
Tasked with guiding his students through a perfect storm of adolescent pressures is Head of Year Mr Moses: an unlikely pacifier of teenage angst.
His job, as a pastoral leader, is to keep every Year 9 student on the straight and narrow. This year, one student proves particularly testing and strikes a chord with Mr Moses.
Meanwhile, not all is complete in the Head of Year's own life: Mr Moses is looking for love.