One One One is a massive cylindrical space station where the only place habitable by humans, or the slothlike Brachiators, is near the center axis. There the humans live in large rope and canvas hammocks, and the Brachiators cling to entangled vines in a precarious ecosystem above the poisonous atmosphere below, where even stranger bioengineered life can be occasionally seen in the form of large flying dragons. Cort learns from the human leaders the details of the murders. The first woman was killed when her hammock ropes were cut with tools not allowed on the station, and the second woman was crucified on the Brachiators' vines with their tools. Cort then interviews all of the 70 other humans on One One One, the AIsource on the station, and one of the Brachiators, who consider humans to be Ghosts, and not among the Living, until they stay among them clinging to the vines long enough to be considered Half-Ghosts.

Soon after arrival, Cort begins to receive threatening video hate mail from an unknown source. Little by little, Cort uncovers more and more clues to the complex puzzle of what is going on about the habitat, developing allegiance with a cyber-linked pair of humans named Oscin and Skye Porrinyard. After an attempt is made to murder Cort in a manner similar to the first murder on the station, and subsequent events convince Cort no humans may be safe, she orders everyone evacuated to the transport docking area and continues her dangerous mission alone, with some assistance from the Porrinyards. With her own life and career now at risk, she slowly uncovers the mysteries of One One One, while also learning secrets about her own traumatic past.

A brilliant sci-fi murder mystery

Adam-Troy Castro has been building an impressive array of short fiction across many genres for almost 20 years, but this is his first original novel (unless you count his collection of humorous SF stories, Vossoff and Nimmitz, as a fix-up novel—most of his other novels have featured Marvel Comics' Spider-Man). Emissaries From the Dead is indeed a brilliantly executed novel, fully successful as both science fiction and murder mystery. Indeed, it evidences a writer at the peak of his career, and it shows none of the flaws one expects from first novels.

The novel is set in the same far-future universe as Castro's award-nominated stories "The Funeral March of the Marionettes" (1998) and "The Tangled Strings of the Marionettes" (2003), and its protagonist, Andrea Cort, debuted in the novella "Unseen Demons" (2002). All three of these stories can be found in Castro's story collection, Tangled Strings (2003), and familiarity with those stories is useful but not essential to reading—and enjoying—Emissaries From the Dead.

Emissaries is a dark and moody novel, featuring a disturbed and misanthropic protagonist with a tragic past, other characters who are indentured to the Diplomat Corps to escape even more depressing circumstances, the inhuman and seemingly indifferent AIsource and the horrific and dangerous environment of One One One. This is the type of novel that in less skillful hands could have become simply dark and depressing, but Castro manages to make the story powerfully compelling throughout. The future he has created is starkly original, especially the mysterious and seemingly omnipresent AIsource, and he handles the pacing and plotting of the murder mysteriously flawlessly. It also helps that Andrea Cort develops as a character in this novel—and by the end is becoming less disturbed and misanthropic, and indeed quite sympathetic and likable.

Emissaries From the Dead is one of the best science fiction novels of the year so far, and it can be recommended especially to fans of science-fiction mysteries.