Michael Portillo strikes oil in the suburbs of Los Angeles, contemplates his navel in the orange groves of Riverside, makes a California roll and paints a pretty picture in Laguna Beach. It is Mexican Independence Day and the locals are celebrating the country's hard-won independence from Spain in the early 19th century. There is dancing, singing and feasting in the streets and Michael joins the party. He learns that half of the population of LA is Latino, mainly of Mexican descent, and hears how after only a few decades, Mexico lost half its territory and California became part of the United States.

Michael learns the secrets of backyard oil drilling in Los Angeles, home to the largest urban oil field in the United States. Nodding donkeys are everywhere - in residential neighbourhoods, parking lots and burger joints. Michael sports a zesty orange jacket to visit the Citrus Variety Collection and learns the difference between a pummelo and a papeda. Alongside oil, the citrus fruit industry, he discovers, is one of the bedrocks of the state's economy. At Laguna Beach, Michael learns how artists from the east coast travelled west on the Transcontinental Railroad to found a colony of 'plein air' painters attracted by the beautiful coastline and glorious light to paint outside.

Clad in khaki boiler suit and sporting dark glasses, he joins the US Navy at Pacific Fleet, birthplace of the elite flying academy, Top Gun. In San Diego, he picks up the trail of the industrialist and property speculator, John D Spreckels, who made the city boom in the 19th century and built a pavilion to house the largest outdoor pipe organ in the world. Michael is offered the chance to play it. Appletons recommends a trip to a huge structure, completed in 1888, on which San Diegans have depended for water for 130 years - the Sweetwater Dam.