The story is set in a parallel version of Earth where an industrial civilization is flourishing amidst the backdrop of an impending war between two bordering nations.
Shirotsugh Lhadatt is an unmotivated young man who has drifted into his nation's lackadaisical space program. After the death of a fellow astronaut, he nurtures a close acquaintance with a young religious woman named Riquinni Nonderaiko, whose faith has seen her through some personal hardships. Seeing Lhadatt as a prime example of what mankind is capable of, along with the godliness and ground-breaking nature of his work, she inspires him to become the first man in space.
His training as an astronaut parallels his coming of age, and he and the rest of the members of the space project overcome technological difficulties, spiritual doubt, the machinations of their political masters, and a botched assassination attempt by the enemy nation. Amidst the debacle, Lhadatt soon becomes worn out by the overbearing publicity surrounding his space mission, prompting him to stay with Riquinni for awhile; he then comes close to raping her one night while catching her undressing, causing a temporary rift between them that is later happily mended.
These events culminate in the eventual space launch, which is taking place in what is essentially a demilitarized zone with the hope that the enemy nation will act to seize the rocket before launch, giving Lhadatt's country a pretext for war. As planned, the enemy nation launches a vast combined arms invasion, resulting in a visually stunning finale as fighter planes duel high above an armoured advance towards a defensive trench network. Despite calls to pull out, Lhadatt, already in the space capsule, convinces the vulnerable ground crew to complete the launch. The launch stuns both sides into inaction as Lhadatt goes into orbit. With no more reference to the world below (beyond a slight suggestion that both nation's plans for war have been foiled by the successful launch), Lhadatt prays for humanity's forgiveness.
In a symbolic moment, Lhadatt's capsule is suddenly bathed in sunlight, and a montage of his own life and his world's history and achievements flash (presumably) through his mind. Meanwhile on the planet's surface, Riquinni witnesses the first snow fall and gazes into the sky, thinking of Lhadatt.