Premise

In c. 2732, the Hegemony of Man comprises hundreds of planets connected by farcaster portals. The Hegemony maintains an uneasy alliance with the TechnoCore, a civilization of AIs. Modified humans known as Ousters live in space stations between stars and are engaged in conflict with the Hegemony.

Numerous "Outback" planets have no farcasters and cannot be accessed without incurring significant time dilation. One of these planets is Hyperion, home to structures known as the Time Tombs, which are moving backwards in time and guarded by a legendary creature known as the Shrike. On the eve of an Ouster invasion of Hyperion, a final pilgrimage to the Time Tombs has been organized. The pilgrims decide that they will each tell their tale of how they were chosen for the pilgrimage.

Part One, The Priest's Tale: "The Man who Cried God"

Paul Duré and Lenar Hoyt are Catholic priests. Duré is exiled to Hyperion. He researches an isolated civilization known as the Bikura. Duré deduces that the Bikura have been infected with cross-shaped parasites called cruciforms. After death, the cruciform rebuilds the physical body and resurrects them. Duré encounters the Shrike and is infected with a cruciform.

Severe pain prevents Duré from either cutting out the cruciform or leaving the Bikura; his journal entries end. Hoyt reveals that Duré crucified himself to a tesla tree in a desperate attempt to rid himself of the cruciform. For seven years, Father Duré had been continually electrocuted and resurrected. As Hoyt touches Duré, the cruciform falls from his body and allows him finally to die. The Bikura are destroyed with nuclear weapons, but not before Hoyt is infected with both Duré's cruciform and one of his own.

Part Two, The Soldier's Tale: "The War Lovers"

Colonel Fedmahn Kassad's tale begins with a flashback to his days training in the FORCE military academy on Mars. During a simulation battle, a mysterious woman saves Kassad and becomes his lover.

Kassad hijacks an Ouster shuttle and crashes it onto Hyperion. There he is reunited with his lover Moneta. Kassad sees the Tree of Pain, a gigantic steel tree on which the Shrike impales its victims. Moneta and the Shrike teach him to use time-altering abilities in combat. Kassad realizes that Moneta and the Shrike have been manipulating him and wish to use him to spark an interstellar war in which billions of people will die. After Kassad is rescued, he becomes an anti-war activist.

Part Three, The Poet's Tale: "Hyperion Cantos"

Martin Silenus trained as a poet, but his training was interrupted when a black hole destroyed Earth. Silenus is forced to work as a laborer. During this time, he starts work on his Hyperion Cantos, his magnum opus. His Dying Earth series becomes an enormous hit, making him a multi-billionaire.

Silenus joins Sad King Billy on Hyperion. Billy is an aristocrat who decides to relocate to Hyperion and establish a kingdom of artists. Silenus resumes work on the Cantos and becomes convinced that the Shrike is his muse. Billy burns the Cantos manuscript and is taken away by the Shrike. In the centuries since, reliant on life-extending treatments, Silenus has been waiting to return to Hyperion to finish the poem.

Part Four, The Scholar's Tale: "The River Lethe's Taste Is Bitter"

Sol Weintraub, a Jewish professor, is present on the pilgrimage with his infant daughter Rachel. Twenty years ago, Weintraub's adult daughter became an archaeologist and went to Hyperion. While mapping one of the Tombs, the Shrike appears; Rachel contracts a disease which causes her to age backwards. Weintraub wrestles for years with dreams in which he is ordered to go to Hyperion and sacrifice Rachel in a replay of the Binding of Isaac. He decides to become a pilgrim and to implore the Shrike for a cure.

After hearing Weintraub's tale, the party retires outside to gaze at the stars. There, they see the Templar treeship which carried them to Hyperion destroyed by Ousters. The ship's captain (who is also on the pilgrimage), Het Masteen, does not react and retires to his room without speaking. In the morning, Masteen is missing and his room is found full of blood, despite a watch that has been kept all night.

Part Five, The Detective's Tale: "The Long Good-Bye"

Brawne Lamia is a private investigator. Her current client is a cybrid (a human body controlled by a TechnoCore AI) named Johnny. She and Johnny are forcibly farcast to a planet that seems to be a perfect replica of Old Earth. They become lovers. Lamia and Johnny undertake a virtual reality heist on the TechnoCore. They discover that the Core AIs are divided by their varying loyalty to the Core's Ultimate Intelligence (UI) project. Some members of the Core plan to create an omniscient AI: in essence, a god.

Johnny is killed in an ambush, but not before he transfers his consciousness into an implant in Lamia's skull. It is revealed that Lamia is pregnant with Johnny's baby. She is rescued by Shrike cultists, and granted asylum by the Church of The Shrike under the condition that she will embark on the pilgrimage.

Part Six, The Consul's Tale: "Remembering Siri"

The Consul tells the story of Merin Aspic and Siri. Aspic engages in several voyages aboard a spaceship to build a farcaster portal on Maui-Covenant, connecting it to the Hegemony and its waiting hordes of tourists. Eventually he falls in love with Siri. Each time they meet, Merin and Siri age at different speeds due to time dilation. This difference grows more pronounced until the eighth visit, in which Merin returns to find Siri dead of old age and the farcaster ready to be activated. Merin chooses to sabotage the farcaster, beginning a hopeless resistance against the Hegemony. In crushing the rebellion, the military destroys the ecology as thoroughly as the tourists would have. The Consul reveals that Siri and Merin were his grandparents. He bides his time, waiting for a chance to betray the Hegemony and achieve revenge. The Consul reveals that he triggered an Ouster device which led to the emptying of the Time Tombs and the release of the Shrike, knowing that doing so would likely cause the destruction of humanity.

Epilogue

The pilgrims decide to continue their journey to meet the Shrike. The narrative abruptly ends as they approach the Time Tombs, which now emit an unusual glow, across the desert plain.