With the boys up early at Madrid's fish market, the ladies lounge luxuriously eating churros and hot chocolate. Then Gwyneth and Mario cruise down to Toledo for a cooking lesson with one of Castilla la Mancha's top chefs. Mark and Claudia travel the route of Don Quijote, tilting at windmills and learning how to make Manchego cheese. That night, the group celebrates Claudia's birthday in style. After eating bird sushi, Mario learns that Iron Chefs don't always have iron stomachs.

Mark's moods swings and insatiable appetite have the road trippers stopping often as they head north to Galicia. While in Ribera del Duero wine country, Mario grills milk-fed lamb in a vineyard. While staying at a traditional county inn, Mario's competitive edge emerges and he and Gwyneth race Mark and Claudia on the Camino de Santiago, a historic pilgrimage route. Back at the inn, Mario and Gwyneth cook dinner while waiting for Mark and Claudia to get back.

Gwyneth, Mario, Mark, and Claudia get down and dirty with the local mariscadoras, digging for some of the world's best shellfish. Later Mario grills up an impromptu feast of lobsters and razor clams paired with the acclaimed Albariño wine. Next the road trippers head inland for wood-fired empanadas. After a day on the water, Mario and Claudia prepare octopus, Galician style, and wash it down with a flaming, boozy beverage.

Gwyneth and Mario meet up with architectural legend Frank Gehry for a tour of the Bilbao Guggenheim. Meanwhile, Mark and Claudia head into the woods where they discover the ultimate grilling restaurant. The foursome reunite at the Gehry-designed Marqués de Riscal Hotel and Vineyard in Rioja wine country. Gwyneth and Claudia opt for oppulent spa treatments while Mario and Mark sneak back into Bilbao to spend a boys‘ night out eating and drinking.

Gwyneth and Mario greet the day at the astonishing Marqués de Riscal Hotel with a behind the scenes vineyard tour. Feeling peckish, Mark joins Gwyneth for some vine-side grilling. Mark and Claudia set out for San Sebastián, where Claudia takes the wheel in the kitchen learning from the master, Chef Juan Mari Arzak.