The play concerns two characters, known as Old Man and Old Woman, frantically preparing chairs for a series of invisible guests who are coming to hear an orator reveal the Old Man's discovery. It is implied that this discovery is the meaning of life, but it is never actually said. The guests supposedly include "everyone", implying everyone in the world; there are other implications that this is a post-apocalyptic world. The Old Man, for example, speaks of the destruction of Paris. The invisibility of the guests implies that the Old Man and Old Woman are the last two people on the planet. As the "guests" arrive, the two characters speak to them and reminisce cryptically about their lives. A high point in the happiness of the couple is reached when the invisible emperor arrives. Finally, the orator arrives to deliver his speech to the assembled crowd. Played by a real actor, the orator's physical presence contradicts the expectations set up by the action earlier in the play.
The old couple then commit suicide by throwing themselves out of the window into the ocean. They claim that life couldn't get any better at this point because the whole world is about to hear the Old Man's astounding revelation. As the orator begins to speak, the invisible crowd assembled in the room and the real audience in the theatre discover that the orator is a deaf-mute.
At the end of the play, the sound of an audience fades in. Ionesco claimed that this sound was the most significant moment in the play, writing in a letter to the first director, “The last decisive moment of the play should be the expression of ... absence,” He said that after the Orator leaves, "At this moment the audience would have in front of them ... empty chairs on an empty stage decorated with streamers, littered with useless confetti, which would give an impression of sadness, emptiness and disenchantment such as one finds in a ballroom after a dance; and it would be after this that the chairs, the scenery, the void, would inexplicably come to life (that is the effect, an effect beyond reason, true in its improbability, that we are looking for and that we must obtain), upsetting logic and raising fresh doubts."