I’m afraid the very phrase “a group of friends, most of them gay men” immediately implies the nature of the mortality that’s central to the book. “The Great Believers” is, as far as I know, among the first novels to chronicle the AIDS epidemic from its initial outbreak to the present — among the first, that is, to convey the terrors and tragedies of the epidemic’s early years as well as its course and its repercussions over the decades. Makkai puts the epidemic (which, of course, has not yet ended) into historical perspective without distancing it or blunting its horrors.

Image Rebecca Makkai Credit... Susan Aurinko

Although it would be impossible, not to mention morally reprehensible, to try to single out the most ruinous period in the AIDS pandemic, those initial years (H.I.V. was first identified in 1983) were terrifying in their own particular way. By 1985, in one of the crueler ironies of the century, gay men had learned that the liberation of the libido, the casting-off of eons-old shame, had exposed them to an implacable, hitherto unknown virus. There was no medication except a drug known as AZT, which was mostly a palliative, and not a very effective one. An AIDS diagnosis, in 1985, was considered a death sentence.

The cohort of friends and lovers in Makkai’s novel live in a constant state of morbid apprehension, first awaiting their test results and then, if the news is bad, awaiting their initial symptoms. Primary among the group (many of whom have already slept with, and infected, one another, back when sex seemed harmless) is a young man named Yale Tishman, recently hired by Northwestern University to help establish a permanent collection for a campus art gallery. Gentle and thoroughly decent, he lives with Charlie Keene, the publisher of a gay newspaper, who is possessive, sulk-prone and just generally a piece of work. For them, as for many, questions about fidelity, and about secrets, take on a new urgency once contagion enters the picture.

“The Great Believers” is peppered with surprises, a minor wonder in a narrative so rife with dreadfully foregone conclusions. As is true of many good novels, writing about it requires considerable navigation around spoilers. Suffice it to say that in the mid-80s sections the grim reaper runs rampant, but there’s no telling who’ll be felled and who’ll be spared. The 2015 sections are, in their way, a detective story. How, after all, does a mother locate her adult daughter, knowing only that she’s somewhere in Paris?

When the novel opens, in 1985, a popular and charismatic man named Nico Marcus has recently died of AIDS, and his family — except for his smart and spirited younger sister, Fiona — prefers to let the cause of his demise go unmentioned. Fiona, who figures peripherally in the mid-80s chapters, moves to the fore in the 2015 chapters, when she, now in her 50s, searches Paris for her lost daughter, Claire, who may have left both a man and a religious cult, and who has no desire to be found.