The Chain of Chance

The Chain of Chance is a novel by the Polish writer Stanisław Lem, published in 1976. Its original Polish title, Katar, literally means "rhinitis", referring to the allergic rhinitis, or hay fever, suffered by several of its characters. Lem approached the detective genre here but transformed it with elements foreign to its tradition: he considers not only several suspects but also the possibility that everything happened by chance, so that the laws of probability and chaos theory become characters and suspects in their own right. This idea, which he developed in his essay The Philosophy of Chance, gives the plot a science-fiction flavour.

The story begins when a detective agency hires a retired astronaut to clarify a series of deaths at a spa in Naples. Several foreigners in their fifties, travelling alone and suffering from allergies, went mad, took their own lives or died by accident after abruptly changing their behaviour. The victims seem to share some link, yet no one can pin it down. After surviving a bombing at Rome airport, the investigator decides to reconstruct the circumstances of the deaths in Paris, where the same chain of unusual events and coincidences recurs.

The key to the mystery is a fortuitous chemical reaction between an antiallergy drug and a hair restorer, catalysed by thiocyanate produced when the body metabolises cyanogen from bitter almonds. The mixture yields a psychotropic compound that causes nightmares, hallucinations and severe depression, eventually stripping the afflicted person of control over their actions. The protagonist suffers its effects, but his professional experience helps him survive and solve the case, tracing the industrial origins of the reagents.

As in Lem's earlier novel The Investigation, there is no single guilty party. The book illustrates the idea that improbable events inevitably occur when the number of interactions is large, a condition that a growing, crowded humanity seems to share with particles. The novel won the 1979 Grand Prix de Littérature Policière in the foreign-language category and remains one of the most distinctive works in the author's fiction.