The Starlight Barking is the sequel to the first The Hundred and One Dalmatians.
Although The Hundred and One Dalmatians has been adapted into two films (animated: One Hundred and One Dalmatians; live-action: 101 Dalmatians), and each version has a sequel film (Patch's London Adventure and 102 Dalmatians), neither sequel film has any connection to The Starlight Barking. Disney archivist Dave Smith said that he was unaware of any considerations for adapting the novel although Walt Disney was interested in doing another project based on Smith's further writings. Author Elizabeth Hand praised the "sophisticated canine society" in the novel. Russ Allbery stated in an online review that, while sometimes predictable, it is "significantly better" than its predecessor and can be seen as "a story of the attractions and perils of sudden advanced technology."
A day of enchantments for the Dalmatians of the first book begins when the Dalmatians wake up and find all the humans and other animals in an unnaturally deep sleep. They hear the barking of Cadpig, carrying all the way from London, where she has become the prime minister's pet. She informs them reports from all over the country reveal the same phenomenon, and summons delegate dogs to London. They travel to London by "swooshing", described as gliding just off the ground.
Pongo and Missus decide to investigate Cruella de Vil to see if she's behind the mysterious events. Joined by Tommy and the white Persian cat, who are "honorary dogs", and a few dogs, they arrive at her house, where the doors magically open for them. However, they find her fast asleep like all the other humans on earth. The dogs then travel to Trafalgar Square where they are addressed from the top of Nelson's Column by Sirius, Lord of the Dog Star, an extraterrestrial dog. Every dog perceives him as a dog of his own breed. Sirius invites them all to travel back to his home where they will be safe from the dangers of nuclear war on Earth, not to mention the whims and potential abuse of humans. Some dogs are for this, some against, but in the end all the dogs agree that Pongo, known for his braininess and heroism, should make the decision.
Pongo joins in a conference with Cadpig and her "cabinet" discussing whether to go with Sirius or not. Then three skinny, mixed-breed strays arrive and ask to be heard. Pongo is sure that they will want to go with Sirius, but they want to stay on earth and someday have owners of their own. Pongo tells Sirius the dogs cannot abandon their humans and the Dog Star sadly accepts the decision. Before he leaves, he grants every dog the power to reach his home before the humans wake up. All the stray dogs take the opportunity to go to the Battersea Dogs and Cats Home.