Besides Pip, two other characters dominate sections of the book. They are the complex, flawed, charismatic and handsome Andreas Wolf, originally from East Germany, now in Bolivia running the Sunlight Project. Wolf is alert to the fame of his rivals in the world of poster-boy computer hacking, Edward Snowden and Julian Assange. If Wolf is self-obsessed, manipulative and concerned with fame and power, Tom Aberant, who runs an online investigative journalism site from his home in Denver (where he lives with his fellow journalist Leila Helou), is his polar opposite. He is quiet, dedicated and serious. Andreas and Tom met briefly at the time of the fall of the Berlin Wall, long enough for them to share a secret.

In what appears to be a set of loose coincidences, Pip ends up working first for Wolf, spending time in his compound near Santa Cruz in Bolivia, and then for Tom and Leila, living in their house in Denver. In both cases, Pip has a funny destabilizing effect on those around her. Leila, unsure of the state of her relationship with Tom, and uneasy about his feelings for Pip, becomes jealous. In Bolivia, Pip moves from being obsessed with Wolf to toying with him sexually, thus making all the young women who have flocked to work for him feel jealous too. There are moments toward the middle of the book where it seems that Pip, having caused a good deal of minor trouble, will finally go home to her mother, who views her movements with immense trepidation, and that this will be a novel about the sentimental and sexual education and the mild expectations of a young and inexperienced young woman in the tough world of now — that it will be, in other words, the modern analog to “Great Expectations” that Pip’s name and circumstances suggest.

At the heart of the novel, however, is a murder, and it is this murder, and the need to keep it covered up, that begin to animate the narrative. Slowly, it emerges that Pip’s ignorance of both her father’s identity and her mother’s real name makes her immensely vulnerable, especially as Andreas Wolf, under pressures of his own, becomes increasingly paranoid. This colorful use of plot, along with the loose, inelegant style and the introduction of multiple subplots and side characters, take their bearings less from Dickens than from Anthony Trollope, and give ­“Purity,” as it captures a society in a state of flux, a leisurely 19th-century appeal.

One of the most vivid sections of “Freedom” contains a character’s private autobiography. “Purity” uses the same device, and once more, this first-person narrative seems the most compelling part of the book as Pip’s father — I will not give his identity away — writes about his years with her impossible and willful mother in passages that are often brilliantly funny. These include a graduation night when the narrator’s ­mother, a woman with ­middle-American cultural tastes, has to watch her son’s girlfriend’s experimental movie in which scenes with a cow in a slaughterhouse are spliced with scenes where Miss Kansas is crowned Miss America. “I’ve had some rough days,” the mother says. “But I think this has been the worst day of my life.”

This is a novel of secrets, manipulations and lies. Like Franzen’s previous two novels, it dramatizes the uneasy and damaging relationships between parents and their offspring in white America, the strains within friendships, and the ways time and familiarity and human failings work at corroding a marriage. It also connects the private and domestic world with pressing public matters. It is, in its way, an ambitious novel, in that it deals with the way we live now, but there is also a sense of modesty at its heart as Franzen seems determined not to write chiseled sentences that draw attention to themselves. He seems content with the style of the book, whose very lack of poetry and polish seems willed and deliberate, a statement of intent.