The series follows the misadventures of an under-qualified schoolteacher named Gerry Duncan, nicknamed Mr. D. It debuted on the CBC on January 9, 2012, and concluded after eight seasons on December 19, 2018.

Creator, writer, executive producer and star Gerry Dee based Mr. D on his ten years teaching physical education in high school before he left for a career in stand-up comedy in 2003.

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.

When Gerry learns that former Olympic champion Donovan Bailey is coming to town, he's determined to seek retribution for a long-standing bone he has with the track "star".

Meanwhile, Lisa attempts in vain to show her appreciation to the staff, and Robert and Bobbi plan for a major shift in the physical education department.

Gerry is in a compromising situation after the teacher auction; Emma enlists Dwyer to do repairs in the library; Trudy gets a surprise visit.

After a near life-and-death experience, Gerry doesn't believe the staff care if he's in mortal peril, so he stages a threat against him prompting Robert to rehire Ron as his security guard.

Lisa feeling dejected being overqualified as a guidance counselor agrees to accompany Brandon to the University where she graduated to help him cope with his anxiety only to get a lucrative offer for a professor position based on her credentials.

All the while, Gerry is challenged by the graduating class, who he started teaching in grade 5 in the series premiere, to provide them a parting gift that they’ll remember him.

Gerry plans on outdoing his predecessors, which he’s encouraged to break the world record for the largest time capsule using a dumpster.

Eventually, Gerry has the students digging up Xavier's grounds to bury the time capsule dumpster, only to stumble upon human bones prompting the local authorities to shut the school down indefinitely.