In a glittering evening scene set in Los Angeles, a snappy, pampered Cocker Spaniel named Gracie lives a life centered on jewelry and status, while Pedro, a timid yet brave British Shorthair, survives on scraps and garbage-food. The two couldn’t be more different, and their paths collide when they are adopted by the same family. Pedro was rescued from a shelter, found scared and terribly hungry, and Gracie soon makes it clear she disapproves of his rough-and-tumble ways. He eats from the garbage, sleeps in her bed, and even molts on her jewelry, which drives Gracie to exasperation. A scuffle erupts, and the family tries to separate them by placing each pet in a carrier, but the tension escalates when Pedro accidentally breaks Gracie’s necklace after she refuses to share her lone can of dog food.
The family heads to Utah for a vacation, and the two pets learn that traveling together may be harder than they thought. Gracie discovers she left her favorite squeaky toy, Mr. Señor, behind and races back to fetch it, while Pedro forgets his cat scratcher and goes back for that as well. Along the journey, they encounter new animal characters who will change their perspective. A helpful condor, Conrad, becomes a resourceful ally, and a stylish bunny named Shades with sunglasses adds a curious spark to the mix. As the boxes carrying the pets reach the airport, they topple off the truck, and Gracie and Pedro awaken to find themselves separated from their families and in a state of chaos. A reckless decision to stow away on a plane backfires spectacularly: the stowaway compartment is compromised, and the two are ejected from the aircraft, leaving them stranded miles from Utah. Gracie panics at the thought of returning home, while Pedro blames himself for the misstep. Faced with the daunting reality, they resolve to undertake a 500-mile trek back to Utah together.
Their journey brings them to a surprising alliance with Willow, a horse who longs to explore the world with his owner, and to the accompaniment of Detective Doyle and his British-ferret companion Sherlock. Pedro urges Gracie to reconsider their path, but she remains determined to press on, even as a dog walker offers a possible lead. The trail takes them through an alleyway and into the clutches of animal control, a setback that deepens Gracie’s understanding of Pedro’s fear of the Pound, a place that holds painful memories for him from his past.
The voyage intensifies when the snake duo Sissy-Chrissy rescue them after a truck stops at a gas station, leading the animals to an underground lair where a viper bite and a grim fate threaten their safety. Pedro volunteers to take the bite, hoping to prove his ferocity, but Gracie’s life hangs in the balance as the danger escalates. They are overheard by a group of cats who had previously slashed their collars, and Gracie and Pedro seize the opportunity to escape. They dive into a sewer river, are pulled into a vortex beneath the city, and are spit out into a distant river. Sissy-Chrissy vow to continue their search and rescue the pets.
When the two reach shore, Gracie reluctantly consents to let Pedro lead the way. Their journey continues by truck, on foot, and by train, until they board a boat delivering cans and hens. Gracie releases the hens in a bid to prove that birds can fly, but the plan backfires and the chickens tumble into the water. The captain, along with Sherlock and Willow, comes to the rescue and places the pets in a crate bound for Utah, guided by Willow’s sense that snow and polar bears await beyond the horizon.
The voyage leads to Antarctica, where the two must confront another set of icy challenges. They attempt to cross a lake of freezing water; Gracie steps onto the ice as it begins to crack, and Pedro must summon the courage he has long hidden. He dives in to pull Gracie to safety, and in a beautiful moment, the two acknowledge how far they have come and apologize for their earlier misgivings, realizing they have become true friends. The threat from Sissy-Chrissy intensifies when the viper’s plan to break the group escalates, but the snakes end up getting impeded by a series of misfortunes—culminating in a dramatic sequence that ends with the snakes being crushed by a cascade of obstacles, eventually sending their threat packing.
Reunited with their owners at last, Gracie and Pedro discover that family can come from all shapes and sizes, and their unlikely friendship stands as a testament to the power of teamwork and perseverance on the road back home.