Dorothée visits London from France to write a book about England. Arriving at her cousin's apartment, which her cousin has allowed her to stay in while they're away, she discovers a horde of cats determined not to leave the premises. Since she can't chase them away, Dorothée must agree to share the apartment with Danny Mogg, the cat gang leader, his half-sister Jenny Furr, his friend P.T. Panther, his father Paolo, Danny's mother-in-law Molly and his father Sebastian. Dorothée has not seen everything yet because these funny cats will not hesitate to wreak havoc.