Felidae

Francis, a smart and cynical cat, moves in with his owner Gustav Löbel into a dilapidated house whose top floor carries a distinctly chemical odor. He begins a curious exploration of the mansion, sniffing around corners and creaking stairwells. The uneasy atmosphere hints at hidden experiments and danger.

During his exploration, Francis discovers a cat corpse that was killed by a neck bite. At the crime scene he meets Bluebeard, a foul-mouthed one-eyed Maine Coon who quickly becomes an uneasy ally. The encounter marks the first sign that something sinister hides in the house.

Another body appears, and Francis realizes the top floor hosts a sect of cats led by Joker. The sect worships an entity named Claudandus and carries out ritual suicides by plunging into an electric current. The discovery expands Francis's concerns from a murder to a broader, sinister conspiracy.

When his presence is detected, Francis is chased across the city's rooftops by the sect's members. He leaps through a skylight to escape, landing outside with the city lights below. This escape marks a turning point as he begins to gather allies beyond the house.

Francis meets Felicity, a blind cat who becomes his informant. She provides crucial information about the Claudandus sect and the rituals they perform. Her knowledge helps him navigate the perilous mystery beyond the house.

Bluebeard takes Francis to Pascal, an elderly, tech-savvy cat who keeps a meticulous list of local feline residents. Pascal informs Francis that Felicity is the latest victim, increasing the urgency to uncover the sect's plans. The revelation tightens the circle around the mystery.

That night, Francis is haunted by a nightmare featuring Gregor Mendel, foreshadowing the genetic obsession behind Claudandus's project. The nightmare underscores the film's themes of heredity and manipulation. It signals that science and malevolence are intertwined in the house.

During a rodent hunt, Francis discovers a video recording that documents the top floor's past as an experimental laboratory. The project focused on a fibrin glue and tissue adhesive intended to close wounds instantly, but most test subjects—stray cats—died in agony. The only survivor was renamed Claudandus by the technicians.

The video explains that Claudandus was the survivor of the experiments and murdered lead technician Preterius before the lab's closure. He was taken in by Preterius's former assistant Ziebold and learned Mendel's laws of heredity. Over years he cultivated a plan to recreate the primal cat ancestor and exterminate humanity.

Francis discovers a crypt filled with hundreds of cat skeletons, realizing the murders have occurred for years. He begins to suspect Joker, the only cat who claims to have met Claudandus, as someone who might hold the missing pieces of the puzzle. The discovery deepens the sense of a long-running conspiracy.

Joker is found dead, confirming that Claudandus's influence reaches far and wide. Frantic for answers, Francis presses on and learns that Pascal may be more than he appears. The investigation tightens around Pascal and his true nature.

Confronting Pascal, Francis learns that Pascal is actually Claudandus. He recounts his backstory, including murder of Preterius and his alliance with Ziebold, and outlines Mendelian-inspired plans to reconstruct the primal cat lineage. He also declares Francis as his chosen successor.

Francis deletes Claudandus's computer records, triggering a house-wide confrontation that ends in a fierce fight and a raging fire. In the chaos, Francis disembowels Claudandus, who mourns his lost innocence as he dies. Francis then carries an injured Bluebeard to safety, escaping the inferno with the resolve to end the terror.