John Scalzi is known for his witty science fiction thrillers. Old Man’s War and its sequels are his take on military science fiction, while last year’s Collapsing Empire was a new foray into space opera. His latest novel Head On is a techno-thriller involving robotic sports leagues and murder, and it’s a book that’s particularly relevant in our own, technological world.

Some spoilers ahead for Head On.

Head On is the sequel to Scalzi’s 2014 thriller Lock In and an accompanying novella, Unlocked: An Oral History of Haden’s Syndrome. In each, he introduces readers to a world that’s experienced a medical catastrophe: a flu pandemic infected and killed millions of people around the world, and left some of the survivors with Haden’s Syndrome, a condition that left them “locked in” to their bodies. They were alive, but they couldn’t move or interact with their surroundings. The US government began a major initiative to help rehabilitate these survivors, known as Hadens, developing neural nets that allowed them to interface with robotic bodies named Threeps (nicknamed for C-3PO from Star Wars), virtual worlds, and people called Integrators, whom Hadens can take over and remotely pilot.

In Lock In, Scalzi introduced readers to Chris Shane, a Haden FBI agent who is partnered with senior Leslie Vann. The pair investigates the murder of an Integrator, which led to a larger conspiracy. In Head On, the pair is once again tasked with investigating the death of a Haden athlete named Duane Chapman. Chapman is a player in a rising sport known as Hilketa, in which the players pilot specially designed robotic bodies and try to sever the head from a randomly selected opponent. His death is a blow to the newfangled sport, which is attempting to jump to the worldwide stage. As Shane and Vann dig into the athlete’s death, they find a variety of suspects and are ultimately led to a full-blown conspiracy involving shady organizations and the future of the Hilketa league itself.

Scalzi never reveals Shane’s gender, reasoning that it would be difficult to distinguish in robotic bodies, also saying that Hadens could effectively control how they look to the outside world. Audible has since released a pair of audiobook editions, each with a different narrator, Amber Benson and Wil Wheaton.

The novel is a fast-paced, compelling mystery not unlike Isaac Asimov’s robot novels. Scalzi takes readers through the logical investigative steps regarding Chapman’s death, assembling a larger conspiracy that’s built on organized crime, money laundering, and more. While the book is a fun diversion, it’s also an intriguing addition to the world that Scalzi set up in Lock In, and it serves as a good parable for how the world deals with — and takes advantage of — marginalized communities.

Scalzi’s Unlocked introduced and defined this world’s backstory and the political undercurrents that have shaped the world as we meet the characters in Lock In. After the moon shot initiative that helped develop the technology that allows (and ultimately subsidizes) Haden’s health care, a bill called the Abrams-Kettering Bill pulls back on that care, ultimately driving the action in both Lock In and Head On. As a result, Head On is largely a book about unintended consequences. The introduction of Threeps and virtual spaces for Hadens brings about the rise of a unique community of individuals with a shared, semiprotected experience of being locked into their bodies. The pullback on their health care leads many to try to find a way to survive, including violent sports that regular humans can’t literally participate in.

But regular people are beginning to catch up. The technology that enables Hadens to survive and interact with the world is beginning to go mainstream. Non-Hadens want to get in on the virtual worlds and robotic bodies that the Hadens require, and there are protesters at Hilketa games who complain that they’re being discriminated against. As the world begins to change, some of these people are beginning to find ways to take advantage of the situation. Hilketa teams charge non-Hadens a premium price to get “premium” features like medical readouts of Hadens during games, while another business person wants to develop a ZipCar-like Haden service for people (primarily non-Hadens) to use the robotic Threeps when they’re not in use.

Ultimately, Head On is a fun, breezy thriller, one that showcases a world that carries with it some extremely astute commentary on some of the real problems that we face in our own. This is an instance where the world feels like it’s a bit more than the sum of its individual parts, and hopefully, we’re not done with it yet.