Despite being shortlisted for both the World Fantasy and the Hugo Awards, The Tainted Cup is not really either fantasy or science fiction. Yes, there is an Empire threatened by enormous, destructive horrors that come from the ocean depths every wet season. And there is a detailed, invented civilization which fights these leviathans using advanced biological techniques. But the book is a solid murder mystery. It features an absolutely delightful, neurodiverse detective, and her equally interesting new assistant.

Anagosa Dolabra is a high-ranking Iudex Investigator, sent to a backwater town not far from the sea wall that keeps the leviathans away. There, presumably, her idiosyncratic behaviors will be less intrusive. Her newly assigned assistant, Dinios Kol, doesn’t actually know very much about her. Din just knows that they have been assigned a gruesome murder case, and that, since Ana rarely leaves her sensory-protected rooms, he will be the one doing the actual legwork.

Almost everyone in this world has been augmented—physically or mentally or both—by carefully developed serums, grafts, spores and implants. Despite rigorous biological and bureaucratic oversight, these improvements can have permanent and debilitating side effects. Din doesn’t know how Ana has been augmented, or if all those augments are functioning properly. Din himself has been successfully augmented to become an “engraver,” able to remember absolutely everything he sees and hears.

Din really doesn’t want to remember the scene of his first murder case, clearly some sort of biological event gone monstrously wrong, but he faithfully collects and brings all the details back to Ana. Her brilliant deductions and his sometimes-unwilling attention to detail are the perfect combination for solving such crimes. They have a wonderfully sardonic relationship leading to a growing mutual respect. This serves them well as additional murders are uncovered and the case edges deeper into the politics of the Empire. They must move closer to danger, too. Some of the murders caused a breach in the sea wall, and it’s only a matter of time before a leviathan makes its way through it.

There are hints that there are more secrets waiting for Ana and Din to find them, but The Tainted Cup is a complete novel without cliffhangers. A sequel, A Drop of Corruption, is already available.