As the play opens, Harold, a playwright and actor, is preparing to kill himself on the stage. He is stopped from pulling the trigger by the entry of a character who asks for an explanation for this act. Harold, impatient with the interruption, is persuaded to divulge the reason for his intended suicide: he has seen through his life-long delusion that he is an ingenious and imaginative playwright and actor. He is in despair that he is getting no roles, and his plays are not being produced. He chooses the theatre for his histrionic suicide because he sees the stage as an extended metaphor for the illusion that life has become for him: unreal, like the action, events and characters in a play.
The stranger claims to be the main character of the play Harold has been trying to write: Johannes Kepler. Kepler, a dreamer who has spent his entire lifetime in imagination’s realms, but who condescended to the ‘real’ world of science, of facts and figures to validate his theory of the harmony of the universe, explains that he, too, had wanted to write and act in plays in his youth; he too had often despaired that his dream about reaching the moon was just a fiction. He talks Harold into postponing his suicide long enough to perform the play in which he (Harold) acts the central character of his own play: i.e., Johannes Kepler.
The events of the play demonstrate to Harold the power of illusion to generate and create truth. At the end of the play the identification of Harold with Kepler is complete. Just as Kepler, in the play within the play, returns to his manuscript of The Dream (in which he is working out, far ahead of his times, a journey to the moon), Harold, infused with hope and renewed with a greater understanding of the power of illusion, returns to play writing.