Setting defines science fiction, and nowhere is this more clear than in Sage Walker’s The Man in the Tree, a hard SF mystery investigating the ultimate locked room case: a murder onboard a generation ship blasting away from a ruined Earth, heading toward humanity’s unknown future. In this pressure cooker environment, the smallest interpersonal rift could mean destabilizing the last hope for the survival of the human race, and a conspiracy would mean the complicity of the essential personnel keeping the ship running. It’s a twisty, tense mystery with science-fictional elements that are integral to the plot.
Kybele is a seedship, built to travel on a 200-year journey to a faraway planet that will house a human colony, a refuge from a resource-damaged Earth. Outfitted with state-of-the-art technology, the best and brightest scientists and administrators, and a fully functional artificial ecosystem, it’s a veritable utopia where everyone seems to be working toward a common goal—until a worker named Cash Ryan is found impaled by tree branches during a routine system maintenance. It’s the third death on Kybele, and the first murde. To head off a possible PR disaster and bring the culprits to light, the execs in charge appoint analyst Helt Borresen as special investigator. With no system in place for criminal justice, a terrorist conspiracy unfolding in the background, and a burgeoning attraction to the prime suspect, Helt must use his analytical and systems expertise to solve the murder before the last shuttle from earth arrives and the Kybele mission is scrapped for good.
The Man in the Tree is among a small number of books to present an interstellar voyage with believable fragility. Kybele‘s crew is 30,000 people, most of whom are essential for running its day-to-day operations—meaning if Helt identifies a suspect, there’s a good chance that person will have to keep performing their duties until a suitable replacement can be trained. Since each passenger was chosen for being the best at what they do, that’s no easy task. The characters even winkingly discuss the idea that generation ships in science fiction usually fail because of the people, not because of a failure of technology. Early on, the primary suspect turns out to be conducting the victim’s autopsy, but Helt has no choice but to let her continue, because she’s the only qualified pathologist onboard. The characters must weigh the possibility they are working in close proximity with a murderer against the knowledge that doing something about it might destabilize the ship’s ecosystem, causing significantly greater harm. It means Helt and his fellow investigators need to be absolutely certain before they make a move. No pressure.
Helt is a fascinating protagonist. He’s just an incident analyst, trained to suss out how and why a system failed, and how it can be prevented from happening again. In an environment with no conventional law enforcement, his becomes a rather unconventional investigation technique. While the Systems Support (“SysSu”) department interviews suspects and tries to connect leads, they model the murder the way they would any technological snafu—just bringing the unpredictability of human interaction into the mix. As they methodically factor in each data point, they are hampered by the “SM Hour,” when the surveillance systems on board the Kybele are taken offline for maintenance—which is, unsurprisingly, when the murder occurred. The unusual approach to investigation and the unconventional ethics that govern life onboard Kybele also serve to obscure evidence that would normally be uncovered quickly during an investigation, enriching the mystery; SysSu is forced to trust semi-reliable statistical models rather than risk confronting the suspects in the style of a conventional detective novel.
When relying on tried-and-true policework is a risk to the future of humanity, the stakes are naturally going to be higher, and the investigation, that much stranger.