A Border Collie named Roger and a cat named Gwen are both secret agents for an organization known as F.A.R.T. (Furry Animals Rivalry Termination). Their mission is to covertly protect and save the world, all while remaining undetected by humans. This unlikely partnership stems from the Great Truce, a decade-long agreement that has quelled the age-old animosity between dogs and cats. Roger, who was once a courageous field agent, now leads a quieter life working behind a desk. Both he and Gwen share a home in the same building in the suburbs of Seattle, where their human friends, Max and Zoe, reside.
Max, a middle school tennis player, faces considerable pressure from his mother to clinch a state championship title. On the other hand, Zoe is the daughter of a struggling musician named Ollie, and they are presently facing eviction due to Ollie's inability to pay the bills.
Their superior, Old Ed, a Golden Retriever, assigns Roger and Gwen the critical task of investigating a conspiracy that threatens to unravel the truce. Together, they enlist the help of Duke, a Rottweiler neighbor, to patrol the area while their communication systems fail them. During their investigations, they are alerted by a dog at the park that the alley cats may possess vital information.
Roger's reluctance to return to field work stems from a traumatic event involving his mentor, who was injured in the line of duty. As he and Gwen interact with the alley cats, they discover that one of them has recently carried out a covert mission involving a wireless phone company, collecting sensitive access codes. Their discovery leads to the realization that someone is working to manipulate electronic signals that only cats and dogs can hear, potentially igniting hostilities once again, which would undoubtedly lead to a future where humans adopt reptiles and birds instead.
Feeling overlooked as their owners grow busier, Roger and Gwen come up with a plan to get Max and Zoe to connect. They decide to hide their phones, thinking that their humans might overlook them when they leave the apartment. Their plan comes to fruition when Max and Zoe end up in the same elevator. To facilitate their bonding, Gwen intentionally shuts down the elevator power, trapping them inside. Meanwhile, Roger and Gwen’s furry friends confront the mastermind, Pablo the Cockatoo, who aims to destroy the fragile peace. Older Ed, who is trapped inside an ice cream truck, informs them that Pablo is currently at the pet store.
While trapped in the elevator, Max admits to Zoe the immense stress he feels from his mother’s expectations. In turn, Zoe shares her struggles regarding the potential loss of their home and her eagerness to help her father write a song to save them from eviction. Their heartfelt confessions lead to an intimate moment where they share a kiss just as the elevator powers back on. However, once they return to Max's apartment, he discovers that Roger has gone missing, prompting him to track him down using Roger's collar GPS.
Upon reaching the pet store, Roger and Gwen are met with unexpected dangers, including facing off against Pablo and his insect minion, Snarky the Tarantula. In the ensuing chaos, Duke manages to save Roger from captivity while battling the minions. As a boy approaches Pablo and begins to understand the gravity of his actions, Zeek, another minion, seals everyone inside while using the frequency against Pablo. With some clever teamwork, Gwen fights off the snakes, Duke subdues the spider, and Roger confronts Zeek.
In a twist of fate, it is revealed that Old Ed feigned his kidnapping to allow Roger a chance to demonstrate his field prowess. After supporting each other and shutting down the disruptive frequency, the pets reunite with Max and Zoe. Zoe plays her father’s completed song for him, and, importantly, Ollie enjoys it so much that he can sell it, thus securing their home.
Thanks to Zoe’s advice to “chill, chill, and chill,” Max successfully channels his anxiety into winning the championship match. In a heartwarming conclusion, the boy adopts Pablo and Zeek (though Zeek is humorously stuck in a dog suit), allowing Roger and Gwen to bask in the fresh air alongside Max and Zoe, who are closer than ever before.
