Blindsight recap

After thousands of alien probes briefly survey Earth, the ship Theseus sends an augmented crew to investigate a signal near a distant dark giant. Narrator Siri Keeton, whose altered brain makes him a skilled interpreter of other people, joins military specialist Amanda Bates, biologists Isaac Szpindel and Robert Cunningham, linguist Susan James and her alternate personalities, and vampire commander Jukka Sarasti. They discover Rorschach, a vast structure that converses with them while resisting every attempt at comprehension. Inside it they encounter agile organisms called scramblers. Study of the creatures and the signal leads to the central discovery: Rorschach is intelligent without being conscious, and its fluent messages are imitation rather than understanding. The encounter kills the crew, Sarasti dies after forcing Siri to recognize what they have learned, and Theseus attacks Rorschach. Siri escapes alone with the findings. On the journey home, transmissions imply that vampires are taking control of Earth, leaving him to warn a humanity whose own consciousness may be an evolutionary liability.

In 2082, a coordinated burst of countless alien objects maps Earth and burns up in the atmosphere, demonstrating that humanity has been noticed. Siri Keeton explains how surgery for childhood epilepsy removed much of one cerebral hemisphere and left him able to model people's behavior while feeling detached from it. That ability becomes his profession: he observes specialists and translates their work for others. His memories of his parents and of his failed relationship with Chelsea show both the usefulness and cost of his distance. When evidence points beyond Earth, Siri is assigned to an expedition intended to learn who sent the survey and why.

Siri awakens aboard Theseus among specialists extensively redesigned for their jobs: soldier Amanda Bates; biologists Isaac Szpindel and Robert Cunningham; and linguist Susan James, whose partitioned brain also houses Sascha, Michelle, and the analytical Cruncher. Their commander, Jukka Sarasti, is a resurrected vampire with exceptional pattern-recognition abilities and a predator's unsettling effect on ordinary humans. The ship's artificial intelligence controls the mission behind him. Their original destination proves to be a decoy or relay, and the trail leads to Big Ben, a dark giant far beyond the familiar planets. Near it they encounter Rorschach, an immense, changing structure. It answers radio messages in human language, but its responses raise doubts about whether communication is taking place at all.

Theseus approaches Rorschach despite intense radiation, violent magnetic conditions, and architecture that seems to rearrange itself. The crew tests the entity's conversation and finds that it can produce polished language without reliably grasping context, suggesting that its apparent personality may be an automated reflection of human signals. Probes and crew enter the structure and encounter scramblers, many-limbed organisms whose speed and camouflage make them difficult to perceive. The humans capture specimens at considerable cost. Laboratory study shows that the creatures perform complex, adaptive tasks despite lacking the neural machinery the crew associates with consciousness. Rorschach responds to intrusion and observation in ways that exploit the team's limits, while stress, injury, and distrust begin breaking down cooperation aboard Theseus.

The captured scramblers demonstrate that sophisticated problem-solving can operate without self-awareness. The crew concludes that Rorschach's conversation is equally empty of comprehension: it has learned to manipulate symbols humans find meaningful while treating consciousness itself as wasteful interference. The mission collapses as Rorschach adapts to every tactic and the humans' competing systems turn against one another. Sarasti violently pushes Siri toward the insight he was sent to report, then dies when the ship's intelligence takes direct control. With the other crew members lost, Theseus commits itself to a final attack on Rorschach and sends Siri away alone as the surviving messenger. During the long return, weak transmissions indicate upheaval on Earth and the growing ascendancy of vampires. Siri carries home the warning that the alien intelligence is dangerous not because it thinks like humanity, but because it can outthink conscious beings without possessing an inner self at all.

The encounter destroys the expedition. Evidence from the captured scramblers and Rorschach's communications convinces the crew that the alien system is extraordinarily intelligent but lacks subjective awareness; it can imitate meaningful speech without understanding it. Sarasti forces Siri into a crisis intended to make him grasp this conclusion, then dies as the ship's intelligence assumes direct control. With the crew lost and Rorschach poised to threaten Earth, Theseus launches a destructive final attack. Siri is expelled in a small craft so that one witness can carry the discovery home. During his long return he receives fragmented transmissions suggesting that resurrected vampires are gaining power on Earth. He is left with a message more disturbing than a conventional alien invasion: consciousness may be an expensive evolutionary accident, and both Rorschach and humanity's altered successors may be able to think more efficiently without it.