The book continues shortly after the previous installment left off, skipping only Severian's journey from the gate of Nessus to the nearby town of Saltus. Having been separated from the rest of the group he was traveling with, Severian pauses his search for them here as he is given an opportunity to practice his art (in this case, execution) on two people. The first was found to be a servant of Vodalus, a revolutionary and traitor to the commonwealth. As the man is dragged out of his home by a mob, Severian glimpses Agia, a woman whose brother Severian had executed, in the crowd. Severian searches for her at the town fair but instead has a conversation with a man, held prisoner in a tent as a sideshow attraction, whose skin is green. The green man tells Severian he is from the future. Severian takes pity on him and gives him a whetstone so that he can free himself by grinding through his chains, thus recalling his mercy to Thecla, another prisoner, in the first book. He does not find Agia and instead returns to town where he later executes a woman accused of being a witch.
Eating dinner with his friend Jonas (who he met at the gate at Nessus) that evening, he finds a letter from Thecla asking him to meet her at a nearby cave. In the cave, Severian encounters and barely escapes a group of man-apes. He cuts off the hand of one of these creatures and when Severian brings out the Claw (a relic he had accidentally been given by a religious order), the wound is healed. Severian has little time to ponder this as he first escapes some unknown creature, only to be attacked by Agia and her assassins outside the cave. Severian lets Agia go and returns to Saltus, where he and Jonas are taken by Vodalus.
Vodalus recalls that Severian saved his life and allows Severian to enter his service. Severian and Jonas attend a dinner with Vodalus where they consume the dead Thecla's flesh, which when combined with an alien substance, allows Thecla's memories to live within Severian. Given the task to deliver a message to a servant in the House Absolute, the Autarch's seat of power, Severian and Jonas set off to the north. They are attacked by strange alien creatures and barely escape. A nearby soldier patrolling the area is killed by the creatures but then revived by the claw. They are then captured by guards of the House Absolute and thrown into an antechamber designed to hold prisoners indefinitely. Severian's claw heals a wound Jonas receives during the night they spend there, then the pair escape some unknown horror through the use a pass phrase Severian remembers using Thecla's memory within him to open a secret door. Walking the corridors of House Absolute, Jonas steps into a mirror and disappears, promising to return. Severian is lost and eventually encounters the Autarch himself, who he swears service to upon being shown a portal to another universe.
Stumbling into the gardens of the House Absolute, Severian is reunited with Dorcas, Dr. Talos, and Baldanders, who are preparing to once again perform the play they put on in Nessus in the first book. Severian participates again, but the play is cut short as Baldanders flies into a rage and attacks the audience, revealing that aliens are among them. The band is scattered and Severian finds them a ways away the next morning, heading north. Talos and Baldanders part ways with Severian and Dorcas at a crossroad, Severian heading toward Thrax and the giant and his physician headed toward Lake Diaturna. The waitress Jolenta tries to have Talos take her with him, but he has no more use for her now that the plays were no longer necessary, and Severian is forced to take her. As they head north, Jolenta tries to commit suicide and eventually dies when they reach an abandoned stone town. Here, Severian sees a pair of witches initiate a dream-like event in which ghostly dancers of the stone town's past fill the area and engage with the witch's' servant, who disappears. The book ends with Dorcas and Severian emerging from a stupor in the stone town, the witches gone.
source: Wikipedia
