Returning home to the quaint town of Medfield from a much-anticipated vacation, the Daniels family is struck by an unfortunate reality - they have been robbed. The patriarch of the family, the esteemed attorney Wilby Daniels, directs his frustration towards the local district attorney, John Slade, a man rumored to have unsavory ties to organized crime, particularly with the notorious warehouse owner, Edward Roshak. Adding to their misfortune, the family experiences another robbery that very night, alongside their neighbors. This double blow fuels Wilby's determination to take matters into his own hands; he decides to run for district attorney in hopes of restoring safety to his beloved town.
Simultaneously, the two bumbling criminals responsible for the robbery, Freddie and Dip, are caught in a scheme of their own. While visiting a local museum, they spot an exquisite Borgia ring and, believing it to be priceless, they snatch it away. Little do they know that the only person willing to buy their ill-gotten gains is Tim, an ice cream vendor who also happens to be the owner of a charming Old English Sheepdog named Elwood. Tim's intentions are noble; he plans to present the ring to his girlfriend, Katrinka, who works as a pastry assistant.
The plot thickens when Wilby learns about the stolen ring, as he is engulfed in a deep-seated fear: the ring bears an inscription that, if spoken aloud, could turn him into a shaggy dog. As fate would have it, on the eve of Wilby's crucial live television debut, Tim accidentally reads the inscription, leading to a bizarre transformation. Thus, Elwood’s essence captures Wilby’s body, causing chaos as he realizes he is becoming a dog. His son, Brian, witnesses the eerie transformation, noting an unexpected growth of shaggy hair on his father. In a frenzy, Wilby, now in canine form, dashes out of the house, bewildering Tim who cannot fathom why his dog can suddenly talk.
Just when matters seem settled, the ring makes its way to Katrinka, who innocently reads its inscription while Wilby is addressing an audience at a ladies’ garden club. This triggers another unexpected change, resulting in a comical uproar as Wilby scrambles to keep his canine tendencies at bay. Meanwhile, Tim is convinced that a talking dog could be a golden ticket to riches, but as he leaves for a moment, Wilby finds a window to return to his human form.
The journey to find the elusive ring leads to a chaotic pie-filling extraction effort initiated by Katrinka and her team, which culminates in a hilarious pie fight. Amidst the chaos, the thieves manage to seize the ring once more, attempting to pass it to an undercover officer. Back at the museum, the inscription is read again, causing Wilby to once again transform into Elwood right in front of a shocked Raymond, who begins to connect the dots about Wilby's peculiar disappearances.
Informed of Wilby's trouble, Slade initially doubts the peculiar story but soon decides to put the theory to the test. Wilby expresses a desire to investigate Slade's possible connection to criminal activities after a successful election. However, when Slade reads the inscription, the ensuing transformation leaves Wilby trapped in Elwood’s body once more, pushing Slade into an obsession with reading the incantation, dangerously close to making the curse shift onto him.
As the mayhem unfolds, Wilby finds himself pursued by Slade, who wields the power of the local police and animal control. His escape leads him to an animal shelter, where he unites with fellow dogs who rally together to help him break free from his predicament.
With the assistance of Brian and Tim, who finally understand the truth behind Wilby's plight, the evidence against Slade’s dealings with organized crime comes to light. They orchestrate a clever trap that lures Slade to Roshak's warehouse, where Wilby uses a tape recorder to gather key information incriminating Slade. In an unexpected twist of fate, the curse backfires on Slade as he repeatedly recites the inscription, transforming him into a bulldog just as Wilby manages to regain his position as district attorney. The story wraps up neatly as Slade faces the consequences of his actions, getting arrested for reckless driving, while Tim pops the question to Katrinka. In a heartwarming conclusion, they all come together to adopt Wilby’s furry companions from the pound, embracing a life filled with friendship and endless adventures.
