Project Hail Mary

Ryland Grace wakes up alone aboard a spacecraft, disoriented and without any recollection of who he is or why he is there. He finds himself in a sterile, high-tech medical bay monitored by a computer voice, which asks him basic questions that prompt him back into consciousness. As Ryland explores his surroundings, he discovers the vessel is named the Hail Mary. Shockingly, he finds two other crew members aboard, both dead and reduced to mummified remains, indicating he’s been unconscious for a very long time.

Gradually, Ryland’s memories return through a series of fragmented flashbacks. He recalls being a middle-school science teacher, ostracized from the scientific community for unconventional theories about life existing without liquid water. He also recalls that Earth’s sun faces an existential threat because a mysterious organism known as Astrophage is draining solar energy, threatening global extinction within a few decades. Eva Stratt, head of an international task force formed to confront this catastrophic event, forcibly recruited Ryland due to his expertise in alternative biology.

Ryland remembers that the mission aboard Hail Mary was humanity’s desperate final attempt to understand and stop the Astrophage threat. His task was to travel to Tau Ceti—a distant star seemingly unaffected by Astrophage—to find potential solutions. His return home was never part of the plan; instead, he was to send data back to Earth via small autonomous probes called Beetles, sacrificing himself to save humanity.

Upon reaching Tau Ceti, Ryland encounters an alien spaceship. After cautious initial exchanges, he makes contact with its lone occupant, an intelligent being from the planet Erid. Ryland nicknames his alien counterpart “Rocky,” and as the two learn to communicate and get to know each other, Ryland learns that the Eridians also suffer from Astrophage infestations threatening their homeworld. Despite vast biological differences—Rocky breathes ammonia, sees via echolocation, and lives under immense atmospheric pressure—the two quickly agree to cooperate to save their home planets.

Together, Ryland and Rocky uncover crucial information: Astrophage is an organism that migrates between stars, seeking carbon dioxide-rich planetary atmospheres to reproduce before returning to feed on stellar energy. This cycle explains the mysterious energy losses in both their suns. Ryland and Rocky hypothesize that the planet Tau Ceti e—which they rename Adrian—somehow naturally controls Astrophage. They journey together to Adrian, hoping to identify the mechanism behind this anomaly.

At Adrian, they discover a life-form they call Taumoeba, which naturally preys on Astrophage, potentially offering a biological solution to stop the energy drain threatening both Earth and Erid. Initially hopeful, Ryland attempts to collect Taumoeba samples by lowering a collection device into Adrian’s atmosphere. However, a catastrophic accident occurs during retrieval, severely damaging the Hail Mary. Rocky heroically saves Ryland but nearly dies from exposure to oxygen, which is toxic to Eridians. Ryland, despite serious injuries, manages to stabilize and heal Rocky. Throughout these challenges, Ryland wrestles with traumatic memories of his forced recruitment by Stratt, who had prioritized Earth’s survival over Ryland’s autonomy. After two members of the planned Hail Mary crew died unexpectedly, Stratt asked Ryland to take their place. Ryland refused, so Stratt imprisoned him and then drugged him before forcibly sending him on the Hail Mary mission. The drugs Stratt gave him caused temporary amnesia, which is why Ryland gradually recovers his memories over the course of the novel.

Returning to the present, further setbacks arise when Ryland and Rocky’s cultivated Taumoeba initially fail to survive in simulated environments, which resemble Ryland and Rocky’s home solar systems. Undeterred, Ryland proposes selective evolutionary breeding, slowly adapting Taumoeba strains to withstand higher nitrogen concentrations. After meticulous trial and error, they successfully develop strains resilient enough to survive in these harsh planetary conditions, giving both worlds genuine hope for salvation.

With their work complete, Ryland prepares to return to Earth. While cleaning fuel tanks contaminated during the Taumoeba experiments, he discovers that evolved Taumoeba strains can penetrate xenonite, the extremely strong material Rocky’s ship, the Blip-A, is entirely constructed from. Horrified, Ryland realizes that Rocky’s spacecraft is now compromised, its fuel supply probably consumed by Taumoeba. Faced with a harrowing choice—either returning home safely or rescuing Rocky, likely condemning himself to die in space—Ryland chooses loyalty to his friend and redirects the Hail Mary in a desperate effort to save Rocky. Before finding Rocky, he sends the Beetles back to Earth so Stratt and her team can use his findings to save Earth.

After a frantic search, Ryland locates the disabled Blip-A. Rocky, severely weakened, confirms catastrophic contamination has left him stranded. Ryland confesses that he gave up his own chance of returning to Earth to rescue Rocky. Deeply moved by Ryland’s act of sacrifice, Rocky insists on finding a solution to Ryland’s survival. Ingeniously, he suggests Ryland might survive on a diet of Taumoeba, as it shares key biochemical similarities with Earth-based life and is abundant aboard his ship. Ryland, initially skeptical, realizes this improbable plan might genuinely sustain him.

Eventually, Ryland settles permanently on Erid. Initially surviving exclusively on Taumoeba, he endures severe malnutrition until the Eridians—grateful and fascinated by their human visitor—adapt Earth-based scientific knowledge to sustain him. They develop synthetic, nutrient-rich food and medical interventions specifically for his human biology. Despite enduring significant physical deterioration from Erid’s powerful gravitational force, Ryland thrives intellectually and emotionally, becoming deeply integrated into Eridian society as a respected educator and scientist.

Sixteen years after Ryland’s arrival on Erid, Rocky delivers monumental news: Earth’s sun has regained its full brightness, confirming humanity successfully deployed Taumoeba to eradicate the Astrophage infestation. Overwhelmed by relief and validation, Ryland finally knows his painful sacrifices and struggles have meaningfully saved humanity. Rocky gently offers Ryland the possibility of returning to Earth; the Hail Mary still functions and could make the journey home. Ryland hesitates—Erid is now his home, filled with meaningful friendships and professional purpose. Although he still might return home someday, he decides to stay on Erid for the time being. After his conversation with Rocky, Ryland goes to a classroom where he teaches a group of excited Eridian youth, which makes him feel full of purpose.