When the Johnsons' Christmas present for Grover is stolen, Calvin and Dave team up to recover the gift in time for the holiday; a nostalgic Tina tries to get into the Christmas spirit by reviving traditions from when Malcolm and Marty were kids.
Dave's patience is tested when Gemma's freeloading sister suddenly shows up with plans for an extended stay; Calvin grows frustrated that Malcolm is still living at home.
Dave puts his professional conflict mediation skills to the test when he offers to help Calvin find out why his employees are quitting.
After Calvin enjoys attending a hockey game with Dave, Malcolm and Marty wonder if their neighbor is rubbing off too much on their dad; Tina decides to enjoy the perks that come with her stardom when she's mistaken for an A-list celebrity.
When Calvin decides to film a local TV commercial for his business, he enlists Dave, Tina and Marty to help; Malcolm considers making a grand gesture when his girlfriend, Sofia, is offered her dream job abroad.
When Grover joins Calvin's youth basketball team, Gemma finds herself at odds with some of her neighbor's coaching methods; Tina and Marty are forced to confront a long-buried Butler family secret.
Tina receives unexpected news; Calvin, Dave and Gemma encourage her to embrace a new chapter by taking a big leap of faith by learning to skydive; Marty helps Grover create a battle bot for a school science competition.
A surprise delivery prompts Dave and Gemma, as well as Calvin and Tina, to examine the power dynamics in their respective relationships.
A near-accident awakens Dave's sense of civic duty, prompting him to team up with Calvin to try to improve the safety of their community; a trip to the county fair turns into a nerve-racking adventure for Malcolm, Marty and Grover.