Cheers ended Season One with a two part episode ending with a cliffhanger. This was a daring move for a show near the bottom of the ratings. By the end of Season Two the series had grown in popularity but still wasn't a Top 20 show. The producers responded by making the finale an even more emotional two-parter.
Sam and Diane's relationship is at a crossroads, mostly due to lingering trust issues. Their problems come to a head when Sam does a magazine interview as an "Eligible Bachelor." In order to make it up to Diane, Sam enlists an artist to paint her portrait.
Phillip Semenko (Christopher Lloyd, in between Taxi and Back To The Future) is yet another foil to Sam: pompous, pretentious, and contemptuous of the bar rabble. Semenko rejects Sam's offer, until Diane recognizes him. Diane's pretentiousness flatters Semenko's ego, and she runs off with the artist to do the portrait behind Sam's back.
This episode runs at lightning pace, moving to the inevitable cliffhanger where Diane leaves the bar with Semenko. There's a couple subplots (Norm discovers the Hungry Heifer, Coach plans a picnic) but this is all about our star crossed lovers. It can only get darker from here.