4 ideas
Kalitin is a Soviet-trained chemist who built an undetectable nerve agent called Debutant in a closed, secret research facility. After the Soviet collapse he defected and lives in Germany under a new identity, ageing and ill. Two officers, Shershnev and Grebenyuk, are sent to kill him, and the plan is to use his own creation against him.
Kalitin treats his poison as elegant problem-solving: a work of pure science or art judged by its precision and its undetectability. That aesthetic and professional absorption lets him think of himself as an author rather than an accomplice to murder. The moral question gets displaced by the technical question of whether the thing works beautifully.
A state poisoning is meant to be technically untraceable in court but unmistakable in meaning to its intended audience. Deniability protects the state legally, while recognizability delivers the warning to defectors and would-be traitors. The weapon's value lies in holding both at once: invisible as evidence, obvious as a message.
The Soviet Union fell, but its secret laboratories, poison stockpiles, and security-service habits carried over into the new state. The men sent to kill act as career functionaries executing an inherited mission, not as ideologues. Regime change on the surface can leave the machinery of violence, and the people who run it, intact.