It is hard for Chihuahua Ember to decide which is worse: a pack of pugs who announce that they are aliens, or the dog park which is filled with large and overexcited dogs--but he is convinced that he and his animal friends must stop the pugs to save the world (for themselves).

Aspiring artist Kacie spends most of her time on Mercer Street with her best friend Nisha, but one day Nisha and her family are gone, and Kacie struggles to understand the changes happening to her street and neighborhood, and what they mean for her life.