Based on Gerry Dee's real-life experiences as a high school teacher before he switched to comedy full-time, Mr. D is a story about a charming, under-qualified teacher trying to fake his way through a teaching job, just like he often fakes his way through life. The premise shines the light on teaching from the teacher's point of view, and as it turns out, teachers don't know everything, especially Mr. D—who struggles to keep one step ahead of his students.
When Mr. D has only one opportunity to meet Paul Henderson and have his priceless Team Canada jersey signed, he won't let Xavier Academy's parent teacher night get in the way...
Jerry makes an impression on the runway of Lisa's faculty fashion show; Robert and Leung team up to track down a vandal.
When Gerry finds out that Robert is trying to charm Xavier Academy's most generous philanthropist into continuing her support, Gerry decides he's going to show up Robert...
Gerry is forced to appoint his arch nemesis Mr. Leung as his new assistant coach. His attempts to put Leung in his place as his subordinate end up backfiring and causing unforeseen problems. Robert’s beloved pet bird quickly becomes a major nuisance when he starts bringing it to work.
It’s Food Drive Month at Xavier Academy, and Gerry is determined to make sure he wins the prize for being the teacher with the class that contributes the most food. Robert and Bobbi are put at odds when the field hockey team and debate team are both counting on their star, Sheila, to attend practice at the same time.
When Gerry is asked to temporarily fill in for an absent phys-ed teacher, he aggressively pursues what he sees as an "audition" to make a permanent move into the gymnasium. Meanwhile, Robert wants to make sure everything is in order at Xavier when a journalist comes to write a story about the school.
Gerry decides to "help" Bobbi with her girls’ self defense class, but ends up feeling emasculated when it becomes obvious that she is able to physically dominate him. Lisa’s lunch causes an uproar in the teachers’ lounge, while Leung has some mysterious packages delivered to reception.
After Gerry has a positive interview for a position with Xavier’s main rival school, he attempts to use it as leverage with Principal Callaghan for the phys-ed position he’s been dreaming of. When Callaghan encourages Robert to take a bigger leadership role, Robert decides an elaborate musical number will show everybody that he has what it takes.