In Dr. Jeffrey Brewster, a Columbia University psychosociologist specializing in communication theory, the fate of humanity unexpectedly rests. When a mysterious alien ship lands in a Kansas cornfield, Brewster is drafted by the United Nations Security Force (Unsecfor) to join a nine-member global delegation tasked with negotiating Earth's first interstellar alliance. The visitors—the Morotans—claim to seek peaceful cooperation, offering advanced technology and protection against their ancient enemies, the reptilian Zugloorans, whom they describe as ruthless conquerors. But as Brewster soon discovers, nothing in this galactic standoff is as it seems.

The Morotans, towering humanoids with centuries-long lifespans, reveal a history of monitoring Earth, having left artifacts on Mars and Venus millennia earlier. Their proposal: a defense pact allowing them to build a detector base in Antarctica to guard against Zuglooran invasion. Brewster's skepticism deepens when a human expedition to Jupiter's moon Callisto uncovers evidence of recent Zuglooran activity—including a buried alien corpse. The discovery triggers global panic, fracturing Earth's fragile unity. Riots erupt, Cold War-era suspicions resurface, and Senator Lloyd Morris, a brash American delegate, leaks classified intel to the Morotans in a bid to secure U.S. dominance.

As tensions escalate, the Zugloorans abruptly land in Moscow, framing themselves as Earth's protectors against Morotan deception. Their arrival forces Brewster and his team—including Russian physicist Alexei Pirogov, British diplomat Sir Adrian Cross, and Indian cyberneticist Pradyot Raman—to confront a dire truth: both alien factions are manipulating Earth to gain strategic advantage in their millennia-old galactic war. With the planet caught in a tug-of-war between two superior civilizations, President Thomas Macintyre of the United States orchestrates a daring gambit. At a high-stakes conference in London, he declares Earth's neutrality, accepting both alliances publicly—a move that traps the aliens in a paradox of mutual hatred.

The Morotans and Zugloorans, unable to tolerate coexistence, withdraw in disgust, leaving Earth sovereign but vulnerable. Brewster's psychosociological insights prove critical, exposing the aliens' reliance on human division and his own species' capacity for unity. Though hailed as a hero, Brewster returns to academia, wary of future calls to service, while Earth turns its focus to self-reliant space exploration.