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.
Tina spends time with the charming new minister she helped select for her church; Calvin suspects the man may be coveting more than just job security; Marty gets a surprise when he finally meets his disruptive, new upstairs neighbor.
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.