Zula Forthrast, an adopted Eritrean, is given a job by her billionaire uncle, Richard "Dodge" Forthrast, at his company, Corporation 9592, which runs an MMORPG called "T'Rain." Zula and her boyfriend, Peter, visit Richard's cat-skiing resort. Desperate for money, Peter sells a database of stolen credit card numbers to a shady contact, who is in fact working for the Russian mob. The transaction inadvertently results in a T'Rain-based ransomware virus infecting the contact's laptop and rendering the only copy of the database useless. Ivanov, a senior gangster behind the deal, tracks Peter down and coerces him and Zula to help him find the virus creators in Xiamen, China.
Upon arriving in China, Peter, Zula, and Sokolov (a former Spetsnaz security consultant hired by Ivanov) locate the virus creators' apartment. The Russian team prepares to raid the apartment, only to be misdirected by Zula into a random apartment, which coincidentally happens to house Islamic terrorists preparing to bomb an international trade conference. In the subsequent gun battle, Ivanov kills Peter, and Abdallah Jones, the head of the Islamist cell, kills Ivanov. The hackers flee the building just before a fire causes the stored explosives to detonate, collapsing the building. Jones flees with Zula as his hostage. Olivia Halifax-Lin, an MI6 agent posted to Xiamen to manage surveillance on Jones, meets Sokolov during his escape from the building, and the two become romantically involved while attempting to flee China. Sokolov believes that Zula is the only blameless person in this ordeal and he is honor-bound to rescue her from Jones.
Jones and Zula covertly fly from China into the Canadian wilderness and move south toward the US border. Jones plans to use Zula to force Richard to help him cross the border using a secret smuggling route known to Richard. Meanwhile, Sokolov is temporarily separated from Olivia and narrowly escapes China by sea, eventually entering the US in pursuit of Jones. Olivia is reassigned by MI6 to locate Jones in cooperation with the CIA and the FBI, but suspects that all three agencies' traditional approaches are inadequate for the task.
These various threads as the characters kidnap, aid, kill, or flee each other are interwoven with a narrative from Dodge Forthrast's point of view, as he gradually becomes aware of Zula's disappearance and begins taking action, along with his brothers. In the meantime, he recalls the founding of T'rain and the roles of the various technical and creative people (Pluto, C+, D-squared, and Skeletor) involved, as well as his Chinese co-founder, Nolan. T'rain is under pressure because it is the moneychanger for the Reamde ransomware, but also because its participants have dropped their affiliation with Good vs. Evil and are now aligning on two sides that try to destroy each other, the Earthtone Coalition (traditional fantasy nerds) and the Forces of Brightness (Chinese computer nerds). Dodge activates his avatar Egdod to follow clues in T'rain as to Zula's whereabouts. As he moves out into the physical world, he contemplates his own mortality.
Eventually, all of the main characters converge on Richard's ski resort and its US-side counterpart, where Richard's younger brother, Jake, lives with a community of Christian isolationists and heavily armed Second Amendment devotees. The terrorists camp near the resort and inform Richard of their hostage, forcing him to lead them into the US while a small team detonates a suicide bomb near a border crossing as a distraction. After being used as bait, Zula manages to escape and sets out to rescue her uncle. Meanwhile, Jones's US-based terrorist cells converge on the community from the south, and protagonists and terrorists engage in a massive gunfight, terminating with the defeat of the terrorists and Jones's death at the hands of Richard.
Three romantic relationships form during the novel, and appear to continue after its end: Yuxia and Seamus, Zula and Csongor, Olivia and Sokolov.
