For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
The first act begins with Mrs. Smith recounting all the things she and her husband have eaten that night and other seemingly insignificant things. Mary, the maid, shows up and announces that some guests have arrived. The act comes to a close as the Smiths hurry upstairs to change.
Act II
Mr. and Mrs. Martin enter at the top of the second act. The couple spends quite a bit of time trying to remember who the other is, even though they apparently live in the same house. The Smiths (who haven't managed to change) join their guests. The group shares stories about nothing for awhile. The act ends when the doorbell rings.
Act III
The Fire Chief kicks off the third act when he arrives, hoping to find a fire to put out. There isn't one, so he shares some obscure fables that don't make any sense. Mary, the maid, enters and we learn that she and the Chief were once lovers. After the Fire Chief takes his exit, the Smiths and Martins begin shouting nonsense at each other. The lights go out and rise again on the Martins in the same position as the Smiths were at the beginning of the play. The curtain slowly falls as the Martins begin the play again, saying the same lines as the Smiths did in the first scene.