The film kicks off with the enchanting song "Once Upon a Time in New York City," setting the stage where a group of kittens, including an orange tabby named Oliver, find themselves being selected by humans. Unfortunately, Oliver is overlooked, leaving him to navigate the rain and seek shelter under a car's hood. Thankfully, the engine's roar awakens him, nudging Oliver out of his slumber, and he quickly realizes he’s hungry.
His first attempt to alleviate his hunger leads him to a nearby hot dog stand, but his effort ends in failure. As we transition to a scene featuring a white, spotted dog named Dodger, we see him observing the tussle between Oliver and the owner of the hot dog stand. Showing some unexpected kindness, Dodger intervenes to assist Oliver in nabbing some hot dogs, although he’s not one to share his spoils.
The screen shifts to display a gang of dogs and, just as the music fades, Dodger presents them with hot dogs he pilfered to help Oliver. Later, we find Oliver perched above the dog gang’s lair, belonging to their master Fagin, before he accidentally tumbles down, causing chaos among the dogs who initially mistake him for an extraterrestrial. After clarifying that he was merely following Dodger, they embrace him.
Fagin soon arrives with dog food, igniting excitement among the dogs until a menacing figure named Sykes arrives, demanding money that Fagin lacks. In a tense moment, Sykes attempts to choke Fagin, only to relent with a warning: he has three days to cough up the cash or face dire consequences. Following this unsettling encounter, Oliver inadvertently falls into the river, yet manages to return to safety.
As he recovers in the hideout, Oliver joins the other animals in reading a book together. The next day, Fagin takes his motley crew of dogs out to hustle for cash, singing along to their rhythm as they plot a heist involving a vehicle—but when Oliver accidentally turns the ignition, it leads to chaos that nearly gets Tito injured.
In a twist of fate, Jenny, a kind-hearted girl, finds and adopts Oliver, while Gorgette, her poodle, disapproves of his presence. This sparks a delightful song that portrays their budding relationship as Oliver settles into Jenny's home. Meanwhile, Dodger and the dog gang plot to rescue Oliver, successfully convincing Gorgette to join their mission.
As complications ensue, Fagin’s greed drives him to concoct a scheme to make money by posing as a catnapper. Unbeknownst to him, Jenny is worried about Oliver’s disappearance and is keen on locating him. Their paths intersect dramatically when Sykes captures Jenny, prompting Oliver, Fagin, and the dogs to spring into action to save her. A pulse-pounding chase unfolds as they navigate the dangers posed by Sykes, leading to a showdown against an oncoming train that ultimately meets Sykes with a tragic end.
The following day, a celebratory atmosphere blankets Jenny's home as Fagin, Oliver, and the dogs gather for her birthday. Throughout the festivities, Gorgette begins to warm up to Oliver and the gang, illustrating a harmonious conclusion. As the second uplifting song plays in the background, the credits roll, encapsulating the adventure that brought these characters together.
