The sorcerer Prospero, former Duke of Milan, and his daughter, Miranda, have been stranded for sixteen years on the island, after Prospero's jealous brother deposed him and set him adrift with the newborn girl. Possessed of magic powers due to his great learning, Prospero is served by a spirit, Ariel, whom he has rescued from imprisonment in a tree. Ariel was imprisoned by the witch Sycorax, who had been exiled to the island years before and died before Prospero arrived. The witch's son Caliban, a deformed monster who was the only non-spiritual inhabitant before the arrival of Prospero, has been compelled by Prospero to serve as the sorcerer's servant.
The play opens as Prospero, having divined that his brother, Antonio, is on a ship passing close by the island, has raised a storm (the tempest of the title) which causes the ship to run aground. Also on the ship are Antonio's friend and fellow conspirator, King Alonso, and Alonso's son, Ferdinand. Prospero, by his spells, contrives to separate all the survivors of the wreck so that Alonso and Ferdinand believe one another dead. Caliban falls in with Stephano and Trinculo, two drunken crew members, and attempts to raise a rebellion against Prospero, but this fails. Meanwhile, Ferdinand, imprisoned by Prospero, falls in love with Miranda. All ends happily, as Prospero forgives his enemies and produces a magical masque to celebrate the union of Miranda with Ferdinand. This is the cue for one of the best-known speeches in Shakespeare (Prospero's final speech), including the lines:
Some recent criticism of The Tempest has interpreted it in terms of colonialism; other readings of the play interpret it as a discourse on the nature of evil; the tempest and the reference to the Bermoothes are seen by some as an early reference to the Bermuda Triangle.