In Beverly Hills, California, Heiress Vivian Ashe leaves her richly pampered pet chihuahua, Chloe, with her irresponsible niece, Rachel, when she is leaving to a business trip. Papi, who is another Chihuahua with an independent kind of personality, has a crush on Chloe, which she constantly rejects. However, when Rachel decides to go to Mexico with her friends, Chloe tries to find her when Rachel leaves her alone in the hotel room. She gets dognapped and is sent to the dog fights in Mexico City, and meets a street-smart German Shepherd named Delgado, a former police dog who was retired after he lost his sense of smell. Delgado helps her escape the dog fights, unleashes the other dogs from their cages, unlocks the ring to allow both Chloe and himself and attempts to get her back to Beverly Hills safely.