There is really very little plot in The Tempest. There is the love story, and then there is the story of two younger brothers who covet their older brothers' titles and possessions. And finally, there is the story of Caliban's plot to murder Prospero. But none of these plots are given much attention or substance; instead, the play is about the complexities of human nature and about reminding the audience that the division between happiness and tragedy is always fragile and must be carefully maintained.
Although The Tempest ends with the promise of a wedding, it could just as easily have ended with tragedy. In this play, there are two murder plots and a betrayal to resolve. In a tragedy, these might have ended with the stage awash in blood, as in Hamlet, but in The Tempest, Prospero's careful manipulation of all the characters and their plans also controls the direction of the action. Prospero's avoidance of tragedy reveals his character's decency and contradicts some critics' arguments that he is an amoral demigod exploiting the natural inhabitants of this island.
The Tempest is unique in its adherence to the three unities. In his Poetics, Aristotle argued that unity of action was essential for dramatic structure. This meant that a dramatic work should have a clear beginning, middle, and end. The unity of time is derived from Aristotle's argument that all the action should occur within one revolution of the sun — one day. The unity of place developed later and is a Renaissance idea, which held that the location of the play should be limited to one place. These unities added verisimilitude to the work and made it easier for the audience to believe the events unfolding on stage.
