The story revolves around the Andersons, an American family who resided in Los Angeles, California. Everything was turned upside down when a strange boy named Jonathan arrived with his dog Adam and claimed to be an illegitimate son of Wilfred Anderson, the wimpy father of the family. That turned out not to be true, but aside from his trickery, Jonathan's kind nature won over the family and they decided to adopt him (and his dog, too). The family had got involved in several misadventures, but despite their dysfunction, they remained a loving family and their relationships with each other and other people even got strengthened.