YOU ARE ONE OF THEM. By Elliot Holt. Penguin. 293 pages. $26.95.

Elliot Holt uses a quote from Samuel Beckett’s “Endgame” as the epigraph to her first novel, “You Are One of Them”: “Then babble, babble, words, like the solitary child who turns himself into children, two, three, so as to be together, and whispering together in the dark.”

Beckett’s line draws attention to the essential loneliness of Holt’s narrator, Sarah Zuckerman, a solitary child who uses the magic of language to supplement what’s missing in her life. But the quote also suggests something more ominous: The desire to manufacture or discover a togetherness that really exists only in the solitary mind.

Couple the Beckett epigraph with a Russian proverb that shows up later in the novel — “Grandmother said two things. Meaning no one can know for sure” — and you have fair warning that “You Are One of Them” will trade in ambiguous reality and narrator unreliability.

Holt sets her novel in two separate time periods, the 1980s and the 1990s. The 1980s, when Sarah is a grade school child, are a time of renewed Cold War paranoia. While her own family is fracturing (sister dying, father leaving, mother panicking), Sarah frets about public fracture, especially the Soviet arms threat.

She and her friend, Jenny Jones, decide to write Soviet General Secretary Yuri Andropov and plead for peace. Jenny Jones lives across the street from Sarah and is everything Sarah isn’t: the cute, charming, and charismatic all-American daughter of an all-American family. It is Jenny Jones’ letter that gets a reply from Andropov, and an invitation to visit the USSR with her family. Jenny’s reign as a goodwill ambassador tracks closely the real-life story of Samantha Smith, whose own reign in the limelight ended with a plane crash when she was 13 years old. Jenny Jones and her entire family also die in a crash.

Sarah survives as the best friend of a child martyr, but over time, she begins to question the symmetry of her friendship with Jenny Jones. In 1995, a further twist of the plot sends her to Moscow. Svetlana, a girl who had befriended Jenny on her goodwill trip to the USSR, emails Sarah to suggest that Jenny’s death was a hoax and to hint that the Jones family defected instead. Sarah finds in Russia a place where everything is up for grabs and anyone might be on the make.

Holt’s descriptions of the natives and expatriates that befriend Sarah are crisp and often funny. It turns out that Russia, a land where the map has been redrawn and everyone is searching for a new source of belief, is a perfect complement to Sarah, who doesn’t know what to believe.

Holt’s novel is most incisive when it is least sensationalistic. Once she moves her narrator to Russia, the novel takes on the tinge of an espionage thriller, with KGB and CIA operatives around many corners. Do not be fooled. In “You Are One of Them,” political infidelity becomes a metaphor for faithlessness of all kinds.

Sarah divides the world into defectors and defectees and counts herself among those who are left behind. “It’s easy to love someone you haven’t let down. In the beginning, the promises are like fresh snow, not muddied by footprints, not yet trampled. You are a hero to the country you defect to, a traitor to the one you defect from.”

The doubleness of leaving — and the question of when to stay and when to bail — is central to Holt’s coming of age drama. Sarah Zuckerman has been, as Svetlana tells her, in “the kindergarten.” To graduate to the main stage, she has to plunge into a world of unverifiable truths, work out the intricacies of personal allegiance and defect from the past.

Reviewer Catherine Holmes teaches English at the College of Charleston.