It's the start of the summer holidays and Megan and Lauren go to the Magic Mountain Rescue Center to bring home two of the cutest, most adorable puppies in the world. With their friend, Caitlin, and her toy dog, Daisy, they start a Puppy Club. But when they hang the Puppy Club medallions on their pups, something mysterious happens—a sudden, dizzying whirl of light whizzes them to Sleuth City and Daisy comes to life Spotting a headline about a missing pooch, the three doggy detectives are soon on the trail of a dognapper—and it's all the girls can do to keep up

The Puppy Club are back in Sleuth City - there's been a major theft from the biggest private art collection in the city. Surrounded by high walls and swarming with guard dogs, the girls can't work out how the thieves did it. But the Mystery Pups' super skills are soon at work, and when they find a mysterious parcel in the attic, the girls are curious. Could it be that the multi-million dollar painting hasn't been stolen after all?