Synopsis

"Jellicle Cats meet once a year ... And make what is known as the Jellicle choice."

- "Invitation to the Jellicle Ball"

The following is a plot summary of Cats the musical. For more context, see the main article of each musical number. Note that this is a general synopsis and some plot details may vary depending on the production.

Act I – When Cats Are Maddened by the Midnight Dance
After the overture, the Jellicle cats gather on stage and celebrate the unique abilities of their tribe ("Jellicle Songs for Jellicle Cats"). The cats then notice that they are being watched by a human audience and proceed to explain how the different members of the tribe are named ("The Naming of Cats"). Slowly the cats disperse, leaving only a white kitten, Victoria, who performs a ballet solo symbolising her coming of age. She is soon joined by Mistoffelees, and together they invite everyone to the Jellicle Ball ("Invitation to the Jellicle Ball"). Munkustrap, the narrator, explains that tonight the tribe's patriarch Old Deuteronomy will make an appearance and choose one of the cats to be reborn into a new life on the Heaviside Layer.

As the Jellicles wonder who it will be, Munkustrap introduces a cat he has in mind: Jennyanydots ("The Old Gumbie Cat"). Jennyanydots is a large tabby cat who is lazy by day, but active by night as she keeps all the household pests in line. As her song comes to an end, the tribe gathers to welcome Jennyanydots, but are interrupted by the entrance of Rum Tum Tugger ("The Rum Tum Tugger"). He is very fickle and unappeasable, "for he will do as he do do, and there's no doing anything about it." The rockstar of the tribe, his number sends the kittens swooning and the adults groaning.

Then, as the cats are revelling in a reprise of Rum Tum Tugger's song, a shabby old grey cat stumbles out wanting to be reconciled; it is Grizabella. Most of the cats back away from her in fear and disgust as Demeter and Bombalurina explain her unfortunate state ("Grizabella: The Glamour Cat"). Grizabella is rejected and leaves. Meanwhile, the gloomy mood is lifted as the music changes to a cheerful upbeat number, signalling the appearance of Bustopher Jones ("Bustopher Jones: The Cat About Town"). He is a fat cat in "a coat of fastidious black" who makes frequent visits to prestigious gentlemen's clubs. Suddenly, a loud crash startles the tribe and the cats run offstage in fright. Hushed giggling marks the entrance of Mungojerrie and Rumpleteazer, a pair of near-identical cats ("Mungojerrie and Rumpleteazer"). They are mischievous burglars who enjoy causing trouble around their human neighbourhood.

The tribe confront Mungojerrie and Rumpleteazer, but are interrupted by the arrival of the Jellicle patriarch, Old Deuteronomy ("Old Deuteronomy"). He is a wise old cat who "has lived many lives" and is tasked with choosing which Jellicle will go to the Heaviside Layer every year. The cats put on a play for Old Deuteronomy, telling the story of the Great Rumpus Cat, a superhero-like figure who single-handedly scares away two warring dog tribes ("The Awefull Battle of the Pekes and the Pollicles"). A sombre moral from Old Deuteronomy is interrupted by a second loud crash, sending the alarmed cats scurrying. After a quick patrol for the villainous Macavity, Old Deuteronomy deems it a false alarm and summons the cats back ("The Song of the Jellicles"). The main celebration begins and the cats display their "Terpsichorean powers" ("The Jellicle Ball").

During the Ball, Grizabella reappears and is once again shunned by the tribe ("Grizabella: The Glamour Cat (Reprise)"). She tries to mimic the other cats' dance moves, but her age and decrepit condition prevent her from doing so ("Memory (Prelude)"). With Old Deuteronomy watching sadly from a distance, she reaches her hand out behind her, hoping another cat will touch and accept her. Rejected once again, she slinks off into the night.

Act II – Why Will the Summer Day Delay – When Will Time Flow Away?
After the Ball, Old Deuteronomy contemplates the true meaning of happiness, referring to Grizabella ("The Moments of Happiness"). However the cats do not understand him, and so with the help of the psychic twins, Coricopat and Tantomile, he has the youngest kitten, Jemima (also known as Sillabub), sing his message in simpler terms.

Gus shuffles forward as the next cat to be introduced, accompanied by his caretaker Jellylorum ("Gus: The Theatre Cat"). He was once a famous stage actor but is now old and "suffers from palsy which makes his paws shake". Gus recalls how he once played the infamous pirate Growltiger and relives his acting heyday in a dream sequence ("Growltiger's Last Stand"). The story of the pirate captain's romance with Lady Griddlebone is re-enacted, ending with Growltiger's demise as he and his Raffish Crew are overtaken by the Siamese.

Back in the present, Gus exits and the tribe's focus turns to Skimbleshanks ("Skimbleshanks: The Railway Cat"). He is the cat who is unofficially in charge of the night train to Glasgow. Skimbleshanks is considered vital to the rail operations, as without him "the train can't start". Within his song, the cats assemble a whole steam train engine out of objects in the junkyard.

With a third crash and an evil laugh, the "most wanted" cat Macavity appears. He is the so-called "Napoleon of Crime" who always manages to evade the authorities. Macavity's henchmen take off with Old Deuteronomy in tow, and as Munkustrap and his troop give chase, Demeter and Bombalurina explain what they know about Macavity ("Macavity: The Mystery Cat"). Macavity returns disguised as Old Deuteronomy but his cover is blown by Demeter. He attempts to take Demeter by force, leading him to face off against Munkustrap and Alonzo ("Macavity Fight"). Macavity has the upper hand initially, but as the rest of the tribe begin to surround him, he shorts out the stage lights and escapes in the resulting confusion.

As the Jellicles fret over their missing leader, Rum Tum Tugger calls upon Mistoffelees for help ("Magical Mister Mistoffelees"). Known as the "original conjuring cat", Mistoffelees can perform spectacular feats of magic. He displays his magical powers in a dance solo and uses them to restore the lights and bring Old Deuteronomy back. With dawn approaching, it is time for the Jellicle Choice to be made ("Daylight").

Before Old Deuteronomy can announce his decision, Grizabella returns to the junkyard and he allows her to address the gathering ("Memory"). With encouragement from Jemima, Grizabella is able to finish her song. She once again reaches her hand out behind her but this time, Victoria takes her hand as a sign of acceptance. One by one, the other cats do the same. Grizabella is chosen to be the one to go to the Heaviside Layer and be reborn into a new life ("The Journey to the Heaviside Layer"). A tyre rises from the piles of junk, carrying Grizabella and Old Deuteronomy towards a stairway that descends from the sky to take Grizabella to the Heaviside Layer. The night is over and Old Deuteronomy recounts to the audience what they have learned about cats, giving a final lesson on how to address a cat ("The Ad-Dressing of Cats").