Bill, Virginia, Libby, Betty, Lester, and Keller all end up at a swingers party hosted by Art and Nancy; Bill and Libby re-examine their complicated relationship; Virginia confronts her feelings toward Bill.
At the office, Bill and Virginia deal with the fallout from the Bucksey case. Afterwards, Virginia informs Bill that he has been invited to a party held at Nancy and Art's house. Bill declines, as he wants to take his kids to see The Love Bug.
Virginia brings Libby instead to the party, to Nancy's surprise. Nancy immediately introduces Virginia to someone who claims to be a friend of Dan's, and that Dan, Mrs. Logan, and him are supposed to be having dinner next week, which Virginia pretends she knows about.
Betty and Lester arrive at the party, and Betty is upset because Helen's parents will be coming to town soon and Helen won't be honest with her parents. In the kitchen, Betty tells Virginia she's playing a dangerous game, as it will soon be revealed Dan and Virginia aren't married when the man has dinner with Dan's actual wife.
Bill shows up at the party, claiming he went home and his kids were nowhere. Libby reveals she did this to Bill for buying the kids a dog without her knowing. The two leave to go back home.
Nancy and Art finally address the party, and it is revealed that they are at a key party with coats. Art, as host, picks the first coat, and picks Virginia's.
Back at the house, Bill and Libby get home to a messy house because of the dog. They get into a brief fight, with Bill claiming that not everything he does is a slight against her. Libby explains her dissatisfaction, but soon into it, Libby demands that Bill perform oral sex on her because she wants to know what it feels like. Bill goes through with it, and afterwards, they discuss their marriage, with Bill claiming that they both did their best.
Virginia and Art go to the bedroom, and Art reveals his dissatisfaction with being in an open marriage.
Betty bonds with the pianist, Guy, and finds out that he is gay as well. She talks to him about the fact that Helen's parents are coming to town and she has to pretend to be the neighbor.
Virginia and Art talk for the remainder of the night, and Virginia finally realizes she still loves Bill.
Virginia leaves the next morning and goes to Bill's house to give Libby her coat, and finds Bill there. Virginia finally reveals to Bill that she and Dan aren't married, and Bill says he knows.
- Michael Sheen as William Masters
- Lizzy Caplan as Virginia Johnson
- Caitlin FitzGerald as Libby Masters
- Annaleigh Ashford as Betty DiMello
The Love Bug was released in March 1969. However, if this episode takes place shortly before the next one (which is set in June/July 1969), this episode should be in May/June 1969.
"Coats or Keys" received universal acclaim, many considering it to be one of the best of the series.