Francis the cat and his owner, Gustav, move into a poorly-maintained apartment with bad smells and rotting parquet flooring.

While visiting the body, Francis notices Deep Purple's sexually-aroused state, suggesting a murderous femme fatale.

He escapes and falls through a skylight into the home of Felicity, a blind cat who heard the murderer and his victims shortly before their death.

Francis experiences another nightmare that night, in which a large portrait of Gregor Mendel comes to life and plays with dead cats.

While hunting for rats, Francis discovers that his home originally belonged to a "Professor Julius Preterius", a scientist who experimented on neighborhood cats, in particular the lab's mascot, Claudandus.

Francis begins to connect his dreams to the murders: he realizes that Pascal's owner was formerly one of Preterius' lab assistants and idolizes Mendel.

In the epilogue, Francis states that he never told any others the true identity of the murderer, and that Joker's name was eventually cleared.

[2] Felidae has become a censored and banned work in recent years, owing largely to Akif Pirinçci's controversial political presence, which includes profanity and crude humour, right-wing statements and inflammatory remarks about issues such as The Holocaust and the immigration of Islamic refugees.

Publisher Random House, the prime distributor for Felidae, cancelled contracts with Pirinçci, ceasing further print production of the book, while commerce giant Amazon removed all print and digital sales pages for the book, except for used copies, which run roughly over US$100 in price.