Timothy Jay Smith’s well-plotted espionage thriller unspools during the chaotic aftermath of the Soviet Union’s dissolution.

Set in Warsaw in 1992, in the disorienting early days after communism’s collapse, The Fourth Courier opens with a body: the latest in a string of murdered “couriers,” each found with a slashed cheek and a bullet to the heart. FBI Agent Jay Porter, dispatched to assist the Polish police because of his family’s nuclear-physics background, soon discovers the killings are connected to something far larger than smuggling. They are linked to a miniaturized Soviet atomic bomb, spirited out of a secret weapons facility by a defecting physicist looking to trade it for a new life in America.

Smith juggles an ambitious web of plotlines, including nuclear smuggling, Balkan war politics, a serial-murder investigation, a custody battle, addiction, and Cold War-hangover bureaucracy. The book’s greatest strength is its atmosphere: Post-communist Warsaw is rendered with real specificity, from currency confusion to bureaucratic paranoia, giving the novel a strong sense of place rarely achieved in genre thrillers.

Its villains, too, are compelling (moreso than its hero). A Serbian nationalist general’s mirror-obsessed narcissism and his female accomplice’s slow-dawning disillusionment with the freedom she’s killed for both linger well past the final page.

The novel is less successful in its tonal control. Extended, graphic sexual content sits uneasily against the geopolitical stakes, and the climactic turn undercuts the tension the book has spent 300 pages building, landing as more deflating than clever. Female characters, meanwhile, tend to exist chiefly in relation to the men around them, and the plot’s reliance on coincidence asks a fair amount of the reader’s patience.

Still, for readers drawn to Cold War-adjacent espionage and morally tangled villains over airtight plotting, The Fourth Courier offers a vivid, ambitious, if uneven, ride through a fascinating and underused historical moment.

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