After a gang of older bullies nearly kills him, slum-child Cort of the planet Aran takes two principles to heart. He will right wrongs, starting with those bullies—and he will save lives, just as a kind soldier saved his that day.
He is on the road to success in the rough metropolis that has grown around the base of the aliens from planet Earth, but his entire world collapses the day his best friend Dilia is abducted. His attempt to free her results only in his imprisonment. He becomes convinced that he can succeed in his mission only with the help of a kiri—an animal companion of hunters in the primeval forest of khena trees where the aliens’ tree-harvesting operations have not yet reached. Cort escapes, but he has become a hunted man.
Meanwhile, Dilia’s bold attempts to escape her captivity result in failure.
Determined to get a kiri and return for Dilia, Cort heads for the forest. Here he fights and overpowers several animals of prey, who agree to help him in his quest.
Cort returns to the city, where he discovers that Dilia has been sold to the commandant of the alien base. When he confronts the commandant, he meets the alien xenologist Lennard, who wishes to study the people of Aran in their native environment. No friend of the commandant, Lennard helps Cort free Dilia in return for being allowed to journey to the forest with him.
Cort begins to suffer terrible and vivid nightmares. Always, he is trying to save his mother or Dilia from Earther soldiers and from the powerful harvesters they use to cut down the khena trees. But he cannot stand against the relentless alien machinery.
The commandant sends his lieutenant, along with a squad of native soldiers to track Cort’s party, kill both Cort and Lennard, and bring Dilia back. In the ensuing confrontation, the lieutenant dies. The soldiers vow to follow Cort.
And Dilia has been damaged during her captivity. She flinches when she is touched. She is uncomfortable around men, and she no longer wishes to discuss marriage. She reveals her fear that she cannot have children—she who loves children so much.
Cort’s dreams grow worse. Only the mysterious creatures called whynywir know how to make them stop. Though both Cort’s people and the Earthers are human, the reclusive whynywir definitely are not. Cort must make the long journey to the distant valley where they live, wearing a white fur that announces him as a pilgrim. The white fur proves frustratingly elusive—until one night a white tiger presents itself as a willing sacrifice. But Cort can no more slay the beautiful creature, silver in the moonlight, than he could make his own heart stop beating. He takes the tiger with him as companion, a living white fur. They reach the whynywir’s valley just as winter sets in, closing the mountain pass and making the return trip impossible until spring.
The tiger dies, leaving Cort alone with the whynywir. Cort finds these beings—avian, telepathic, and sharing a communal consciousness—disagreeable, but as he learns patience, they begin to teach him. His full name, he learns, is Corodh-an-aran, protector of his planet, like his father whom he never knew. And all the white tigers on Aran will die in a year or so, when the alien harvesters reach their home.
Cort learns that the spirits of all creatures are reborn time and again. Unlike humans, the whynywir remember their earlier lives. They tell him that at last the spirits rest in the great khena trees of the forest, dreaming of tranquility and singing the chords of the planet’s being. Only now, the dreams of the khena have turned to nightmares. Cort’s nightmares.
Armed with an iron determination to drive the aliens with their monstrous harvesters off his home planet, Cort vows to destroy the base. He gathers around himself those who came from the city—soldiers who are now integrated into forest life, the alien Lennard, and gentle Dilia, who wants to save the children of the city.
While attempting to infiltrate the starbase, Cort becomes a prisoner of the slumlord again—and he is scheduled for execution the following day. He cannot escape. But he takes comfort knowing that he will be reborn Corodh-an-aran again as always. And he will never give up the fight for his planet. He goes to his execution with dignity and at peace—until the slumlord arrives for the festivities wearing Cort’s white tigerskin. And all of Cort’s rage for justice returns. He will not—he cannot—let the tigers die.
A tiny but deadly snake is hiding in the tigerskin, At Cort’s command, the snake kills the slumlord. Cort makes his escape and with his soldiers takes over the aliens’ power plant, driving its rods deep into the core, and triggering a volcanic reaction.
Quakes shake the area. Lava flows. A steady rain of hot ash envelopes the starbase.
Cort finds the commandant and tells him to gather his people and leave with their starship while they still can. Cort returns to rescue his men from an attack by the last of the aliens’ soldiers, and they make their way through the mounting ash and away from the dying City.
In the gathering gloom, he sees the flare of the starship’s thrusters as the last of the aliens depart, leaving Cort’s world free at last. The planet’s nightmares— and Cort’s—have ended.
