The following version of the novel is used in the creation of this study guide: Crouch, Blake. Upgrade. Ballantine Books. 2022. Hardcover. First Edition.

Part One begins in Denver as Logan Ramsay and his partner, Nadine, arrest a known genetic trafficker named Henrik Soren. After they threaten to extradite him to China, Soren gives them the address of a DNA lab. When they enter, however, Logan is caught in an explosion that nearly kills him while infecting him with an unknown virus. After 14 days in quarantine, Logan is cleared of all potential side effects and allowed to return home.

Over the next few months of sick leave, Logan feels constant growing pains and learns that his bones are abnormally dense. As his mind becomes sharper, Logan is captured and locked in a secret facility by his employer, the Gene Protection Agency. There, he learns that his mother Miriam- who inadvertently caused the Great Starvation that led to Logan’s temporary imprisonment- is actually alive and is likely the one who gave him the genetic code that is changing his body.

An unknown amount of time later, Logan is rescued by his sister, Kara, who is revealed to also have been genetically enhanced by their mother. The two are able to decipher a message their mother left in their DNA sequences that leads them to her body in a national forest near Santa Fe. There, they recover a series of hard drives and a video from their mother explaining that she created a genetic upgrade program for humanity. She believes that sentimentality is stopping humans from saving themselves from likely extinction and that the only way to change it is to shift humanity's thinking from emotion-driven to purely rational. Kara agrees, but Logan argues that would erase the part that makes people human. At an impasse, Kara turns off all of her emotions and tries to kill Logan. He escapes with his life, but she claims the hard drives.

Part Two opens one year later as Logan lives in solitude while relying on private investigators to find Kara. He has claimed a new identity, Robbie Foster, but feels disconnected from humans the longer he has his upgrade. However, when he learns of a sudden, unexplainable illness affecting people’s brains in Glasgow, Montana, Logan realizes that Kara released a trial of the Upgrade there. However, while some survive the process, others suffer a catastrophic mutation that causes their brains to shred, killing them.

After interrogating one of Kara’s allies, Logan finds her in their mother’s hideaway lodge in Colorado. Kara admits she is close to creating a transmissible version of the Upgrade and is willing to accept the billions that will die. Logan argues that humans need compassion, but Kara refuses to listen as Logan realizes she has further upgraded herself. Determined to stop her, Logan synthesizes an extremely dangerous collection of DNA nanoparticles. While he returns to D.C in hopes of seeing his family before attempting the second upgrade, Logan realizes they are safe without him and injects the DNA.

In Part Three, Logan’s second upgrade is successful and he uses it to track down Kara with the help of Edwin and a reluctant Nadine. After a fierce climb through Kara’s secret laboratory, Logan shoots her as military operatives arrive. She tells him that he has to do something to save the world and dies in his arms. Logan escapes as Kara’s work is destroyed, and he dumps the rest of her virus injectors into the river, allowing himself to grieve.

In the epilogue, Logan talks to Beth and Ava for the first time in four years. He gives them the journal he wrote during his search for Kara, as well as a letter that he asks them to read once they are done celebrating Ava’s graduation. There, Logan explains that he knows Miriam and Kara were right about the impending end of the world. However, he believes that humanity is lacking the capacity to empathize with those outside of their communities. So, he developed, tested, and released his own upgrade that targeted the specific genes that inhibit humanity’s compassion. Already seeing favorable results, Logan hopes that Ava can inherit a better world and tells them to be happy, even if he can never return.