It's pretty much just a half hour of Edith, Mike, Gloria, Lionel and some other couple playing a game called Group Therapy, but Mike gets upset when everyone on the game rips on him and disagrees with whatever he says. Yep, just 22 minutes of people ripping on Mike and Mike getting frustrated.
So, you may ask, why the perfect score? It's a funny episode. Mike freaking out and throwing the game on the floor, that woman having to sit on someone's lap who was 'making her nervous', Mike giving Archie a hug (Edith may be slightly dumb and gullible a lot of the time, but she is pretty smart in the last scene of this episode), etc. It's a decent episode with a good ending. A+