Cándido Rincón (33) and América (his pregnant common law wife, 17) are two Mexicans who enter the United States illegally, dreaming of the good life in their own little house somewhere in California. Meanwhile, they are homeless and camping at the bottom of the Topanga Canyon area of Los Angeles, in the hills above Malibu. Another couple, Delaney and Kyra Mossbacher, have recently moved into a gated community on top of Topanga, in order to be closer to nature yet be close enough to the city to enjoy those amenities. Kyra is a successful real estate agent while Delaney keeps house, looks after Kyra's son by her first marriage and writes a regular column for an environmentalist magazine.

The two couples' paths cross unexpectedly when Cándido is hit and injured by Delaney, who is driving his car along the suburban roads near his home. For different reasons, each man prefers not to call the police or an ambulance, and Delaney soothes his conscience by giving Cándido "$20 blood money," explaining to Kyra that "He's a Mexican." From that moment on, the lives of the two couples are constantly influenced by the others.

After the accident, Cándido's problems deepen. When he does not find a temporary job at a local work exchange anymore, he unavailingly tries to find one in the city, hoping to save money for an apartment in the North despite the low wages offered. With América pregnant, his shame at not being able to get a job and procure a home and food for his family increases, especially when América decides to find some illegal—and possibly dangerous—work herself. At one point in the novel, after Cándido is robbed by some Mexicans in the city, they are forced to go through the trash cans behind a fast-food restaurant so as not to starve.

The Mossbachers are also having problems, though of an altogether different nature. Comfortably settled in their new home, they are faced with the cruelty of nature when one of their two pet dogs is killed by a coyote. In