Monk is preparing to spend a quiet Christmas at home, until his father, Jack, who he hasn't spoken to in 40 years, rolls into town! But dad's not sticking around -- he's a truck driver with a tight delivery schedule. Leaving behind Natalie's holiday party and all that is familiar to him, Monk joins his estranged father on the road. While trying to repair their relationship, Monk discovers that his father is entangled in a dangerous mystery and the two men must put aside their differences to solve the case. Dan Hedaya guest stars as Jack Monk.