The first biography of Algren was published in 1989 — too soon after his death for reconsideration of a novelist whose emphasis on the unfortunate was then deeply at odds with American culture. Another biography, published in October 2016, appeared in the run-up to Donald Trump’s election as president. The timing of Asher’s book, by contrast, is fortuitous, because many Americans are now preoccupied by economic and class disparities in ways not seen since the Depression. Asher also obtained access to a virtually unredacted copy of Algren’s lengthy F.B.I. file.

Asher claims that Algren was a member of the Communist Party in the 1930s; certainly he was involved in causes and organizations supported by the party. In 1950, the F.B.I. stepped up its surveillance of Algren after Louis Budenz, a former managing editor of The Daily Worker who had renounced communism, told an agent he had heard that Algren was a “loyal member of the Communist Party.” Asher chronicles meticulously the kind of government intrusions whose petty cruelty can still shock. Phone calls were made to his mother, Goldie, who on one occasion, assuming that the agent on the other end of the line was a friend of Algren’s, “bragged about her son’s accomplishments at length.”

In 1953, Algren was denied a passport to visit France — a common tactic used against those suspected of communist leanings at the time. He was not able to travel abroad again until 1959. The long period when he could not visit Beauvoir in France certainly did their relationship no good, but she was never going to leave Paris and her stifling relationship with Jean-Paul Sartre, and Algren was not going to leave the United States. After making a trip to Paris in 1959 to reconnect with Beauvoir, Algren never saw her again. Nevertheless, when she was buried in Montparnasse Cemetery in 1986 (alongside Sartre, of course) Beauvoir was wearing a ring Algren had given her.

The literary gossip in this biography, much of it drawn from letters, is intriguing, witty and sometimes acidic. After “Golden Arm,” Ernest Hemingway wrote Algren a letter comparing him favorably to “the fading Faulkner” and “that overgrown Lil Abner Thomas Wolfe.” Against this backdrop, Hemingway wrote, Algren “comes like a corvette or even a big destroyer when one of those things is what you need and need it badly and at once and for keeps.”

Asher never quite arrives — this is a compliment, not a criticism — at a persuasive explanation for Algren’s long literary decline, before his death in Sag Harbor (he had finally left Chicago), on Long Island. The F.B.I. pressure of the 1950s is insufficient to explain why, in the 1960s and ’70s, Algren did not practice his craft with his earlier diligence. Asher may be right to speculate that the verdicts of the Cold War critics, frequently dismissing Algren as a semi-educated lunkhead (who just happened to worship Dostoyevsky and Chekhov), have had an outsize influence on his reputation.

But when a great writer stops writing, something internal as well as external is always in play. We are currently experiencing a revival of interest in writers — white and black, male and female — shaped by the uncertainties of the 1930s in ways that resonate strongly today. This biography provides an invaluable introduction to one of the best of them.