Oz and James return to the opulent Napa Valley. James is dismayed that Cabernet is a trophy to be paraded here, rather than a wine to be drunk and enjoyed. But at Bill Harlan's estate, a vinery making fine wines that regularly get ratings of 100/100, he concedes that he may have become a wine snob. As they drive home in the now-battered RV, they discuss where their next adventure will take them.

The odd couple are reunited on Muscle Beach where Oz won the World Wine Tasting Championships in the 1980s. His bubble is soon burst when James reveals his vehicle of choice for their road trip, a 42ft monster motorhome which they will share for four hot, cramped and sweaty weeks.

The duo tour the San Francisco Bay area in a classic British Mini and receive a history lesson as they visit vineyards more than 100 years old. They learn about the impact of Prohibition, and James is impressed when Oz finally finds a notable American wine that is both affordable and accessible.

They meet Mike Benziger, owner of an organic estate. He maintains an insectry, where he breeds insects to eat the lesser bugs that damage his vines, and a sceptical James is silenced when he tastes the wine. Next, they visit the Gallo estate, a producer of affordable wines that flood the international market. Their hostess, Gina Gallo, is charming, but Oz and James sour her hospitality by having another argument.

The Rhône Valley provided ample opportunity to learn about lots of different grape varieties. However, the world-renowned winemaker Michel Chapoutier provides an obvious distraction for James with his classic car collection. The father and son team of Domaine Viret, Alain and Philippe Viret, managed to extol the benefits of embracing ‘cosmoculture’, a mystical approach to grape growing involving the harnessing of the cosmic energy of the sky. And Former French rugby international and winemaker, Gérard Bertrand, challenged James to blend his very own wine using a variety of grape extracts.

Oenophile Oz Clarke takes novice James May on a month-long trip around California's wineries. In this third episode, Oz and James are on the coastline of Monterey County. All manner of non-wine tasting related activities ensue, including muscle car racing and rifle shooting with an eccentric millionaire.

Oz Clarke's attempts to educate James May about the pleasures of wine take them to California's outlaw country, where Jesse James hid and James Dean died. The Top Gear presenter is impressed by the wine and its rebellious makers, but most excited by the Harley he uses to tour the second vineyard

The duo headed to Alsace and Burgundy for a lesson on barrel making, and ‘terroir’ - a catch-all way of describing the many factors that can influence the quality of a vineyard. Oz then took a sceptical James to meet one of Burgundy’s most celebrated winemakers, Thierry Beaumont, to sample Burgundies from Thierry’s three separate terroirs.