It was supposed to be HBO’s next big thing: a high-concept drama from the creators of “Game of Thrones,” set in an alternate America, where the Southern states had seceded from the Union and slavery continued into the present day.

Instead, the new series, called “Confederate,” has provoked a passionate outcry from potential viewers, who are questioning how HBO and the creators will handle this volatile mixture of race, politics and history. Several historians and cultural critics are also skeptical about whether the creators of “Game of Thrones,” David Benioff and D. B. Weiss, are the right people to address the subject and if it should be attempted at all.

“Confederate” arrives at a time when many minority groups feel their civil rights are under siege, and when issues surrounding the Civil War and its legacy — the propriety of displaying Confederate flags; the relocations and razings of Confederate monuments — continue to confront Americans almost daily.

To the show’s critics, its promise to depict slavery as it might be practiced in modern times is perhaps the most worrisome element of “Confederate.” They say that slavery, a grave and longstanding scar on the national psyche, especially for black Americans, should not be trivialized for the sake of a fantasy TV series.