I often said to my literature students that they had to judge a novel on what it aimed to do, not on what they wished it to do. This doesn't mean one can't question a writer's choices, only that one should try to enter a novel by acknowledging the writer's guidance through an imaginary world and not by hoping to determine one's own path through that world.
Colson Whitehead's latest novel, The Underground Railroad, repeatedly reminded me of my own advice, and though I felt let down by the end, I think Whitehead accomplished what he set out to accomplish, leaving me to conclude that I wish he'd set out to accomplish something a little different (and to recognize that as my problem, not his).
I knew nothing about the novel when I began, so the turn that it takes (perhaps 50 pages in) from realism to a realism set in an alternate American history knocked me sideways and made me smile. "Ah, so it's not this kind of book, it's that kind of book." But that was wrong, too. Though Whitehead makes the underground railroad a literal (if modest) railway, and though Whitehead makes each American slave state its own imagery realm with its own rules, the fantastical nature of these elements remains restrained. The railroad is the one impossible element; the divergent histories of the states are, as presented, credible.
Much as Ellison's Invisible Man places each conflict experienced by its narrator in a different milieu, varying the level of satire and surrealism within each milieu, Whitehead gives us stories in each American state that somewhat reset the narrative terms for our protagonist, who now has some wholly different tale to navigate. But Whitehead also provides threads that bind Cora, the escaped slave, to a larger narrative, and characters carry over, so there's a sense of the past being buried and then resurfacing with each new "adventure," as in a picaresque novel with a pursuing villain who pushes us to the next tale-within-the-tale—or as in an America in which succeeding generations have found legislative and cultural ways to stifle black progress and re-devalue black lives.
Also echoing Ellison, we see the multitudinous ways black Americans have been afflicted by the culture that abducted and oppresses them. Had Whitehead stuck to a realistic historical framework, we'd have likely seen only the familiar forms of early-to-mid 19th century enslavement. Whitehead instead borrows images and ideas from later in black history, raising issues of education, objectification, white alliances, financial independence, sexuality, and enculturation.
While reading, I felt Whitehead spending more time than I wanted detailing scenes whose details didn't contribute to the book's themes and motifs. Given how the book turned aside from its strictly historical moorings, I felt the writing should have left behind a reliance on the necessities of historical fiction; I grew impatient. However, the resulting novel is a vivid creation, giving us alternate worlds that gain in heft by using details from our history while tweaking the when and where enough to make us question both past and present.