Part of what makes Shakespeare’s “The Tempest,” playing at the Shakespeare Theatre in Washington until January 18, feel masterful is the way Shakespeare moves among his young lovers, long-estranged brothers, supernatural beings, and tremendously human clowns and drunks. But for a contemporary viewer, there is one display of Shakespeare’s virtuosity that does not fit so neatly with the rest.

The storyline, involving Prospero (Geraint Wyn Davies) and Caliban, Prospero’s slave (played here with great sensitivity by Clifton Duncan), is difficult to watch as just another romp. Caliban need not necessarily be played by a black actor: He is described variously as “freckled,” the child of a mother from Algiers and “not honour’d with / A human shape.” But he is often presented as nonwhite and played by nonwhite actors (as he is here). And at the end of a year in which, as Gene Demby put it, the killings of African Americans by police “gave a new birth of passion and energy to a civil rights movement that had almost faded into history, and which had been in the throes of a slow comeback since the killing of Trayvon Martin in 2012,” the struggle between Caliban and Prospero feels deadly rather than playful.

Caliban and Prospero are each unreliable narrators.

In Caliban’s telling, Prospero wooed him, stealing his knowledge of the island where he grew up, and then betrayed him, enslaving Caliban and denying him the control of the island that was his birthright through his mother, the sorceress Sycorax. “When thou camest first, / Thou strokedst me and madest much of me, wouldst give me / Water with berries in’t, and teach me how / To name the bigger light, and how the less, / That burn by day and night: and then I loved thee / And show’d thee all the qualities o’ the isle,” Caliban tells Prospero. Prospero insists that things went very differently: After he was robbed of his dukedom in Italy and sent into exile, he elevated Caliban beyond his condition, and then was himself betrayed: “I have used thee, / Filth as thou art, with human care, and lodged thee / In mine own cell, till thou didst seek to violate / The honour of my child.”

Shakespeare wrote “The Temptest” in 1610 and 1611, potentially inspired by the wreck of a ship sponsored by the Virginia Company. Twenty enslaved Africans arrived in Jamestown, the colony founded by the company, in 1619: British pirates had stolen them from another ship, crewed by Portuguese slave traders. But even if Shakespeare could not observe or read accounts of the early relationships between British settlers and the people they enslaved in increasing numbers as the century wore on, Caliban’s bitterness and Prospero’s accusations of sexual violence have been echoed in countless conversations down the years.

Ethan McSweeny, who directed the Shakespeare Theater’s tremendous recent production of “A Midsummer Night’s Dream,” stages “The Tempest” to suggest that if Caliban is ill-tempered, he has good reason.

Prospero justifies his enslavement of Caliban — who is costumed in a chain — with the proud tilt of his head and a deep conviction in his own superiority. When the drunkard Stephano (David Quay) and clown Trinculo (Liam Craig), who meet Caliban after they are shipwrecked on the island, dub their new acquaintance “monster,” the word stings with stupidity and meanness: They’re too sodden and foolish to recognize the cleverness and desperate hope of a man who is willing to help them gain a kingdom in exchange for only mild betterment in his condition.

Stephano dreams of the pleasures of a private island while forgetting the bloody work he will have to do to earn it. “This will prove a brave kingdom to me,” he muses happily. “When Prospero is destroyed,” Caliban reminds him. Stephano’s response is that of every white person who has counseled patience in the face of urgent need: “That shall be by and by: I remember the story.” He sounds a little like Ava DuVernay’s Lyndon Baines Johnson (played by Tom Wilkinson) in “Selma,” her Oscar-contending movie about Martin Luther King Jr. and the lead-up to the Voting Rights Act.

Ultimately, Stephano and Trinculo are distracted by a line of fancy laundry flapped at them by the sprite Ariel, who exploits their short-term greed to divert them from the greater gain they — and certainly Caliban — might have made by deposing Prospero. “What do you mean / To dote thus on such luggage?” Caliban asks them, confounded by their foolishness.

As the plan to steal Prospero’s books and kill him falters, Caliban warns that “We shall lose our time, / And all be turn’d to barnacles, or to apes / With foreheads villanous low.” Caliban is speaking of the literal danger that Prospero will transfigure them by magic. But in metaphorical terms, his fear comes to pass. Racist imagery that compares people of color to monkeys and denigrates them as animals is such a fixture of our speech that North Korean agencies have repeatedly used such language to refer to President Obama.

At the end of “The Tempest,” Prospero and Caliban reach an uneasy reconciliation. Prospero forgives his slave for having attempted to usurp him, and Caliban vows “I’ll be wise hereafter / And seek for grace.”

But though Shakespeare ends the play with Prospero alone on the stage, commending himself into the audience’s hands and asking us to imagine a happy ending for him, there are intriguing possibilities in Caliban’s final words, in which he blames himself less for his rebellion than for his choice of allies. “What a thrice-double ass / Was I, to take this drunkard for a god / And worship this dull fool!” Caliban says in self-recrimination, but not quite in surrender. A truly wise person knows the difference between freedom and servitude to a master who fancies himself benevolent, between true allies and false ones who only seek their own advantage. We can imagine Prospero happily back in Milan, but Duncan’s performance invites us to dream of what his departure might mean for Caliban, too.