In January, 2015, American rock climbers Tommy Caldwell and Kevin Jorgeson captivated the world with their effort to climb the Dawn Wall, a seemingly impossible 3,000 foot rock face in Yosemite National Park, California. The pair lived on the sheer vertical cliff for weeks, igniting a frenzy of global media attention. But for Tommy Caldwell, the Dawn Wall was much more than just a climb. It was the culmination of a lifetime defined by overcoming obstacles. At the age of 22, the climbing prodigy was taken hostage by rebels in Kyrgyzstan. Shortly after, he lost his index finger in an accident, but resolved to come back stronger.
When his marriage fell apart, he escaped the pain by fixating on the extraordinary goal of free climbing the Dawn Wall. Blurring the line between dedication and obsession, Caldwell and his partner Jorgeson spend six years meticulously plotting and practicing their route.

In this episode, Helen seeks out the colours that turned planet Earth multicoloured. To investigate the essence of sunlight Helen travels to California to visit the largest solar telescope in the world. She discovers how the most vivid blue is formed from sulfur atoms deep within the Earth's crust and why the presence of red ochre is a key sign of life. In gold, she discovers why this most precious of metals shouldn't even exist on the surface of the planet and in white, Helen travels to one of the hottest places on Earth to explore the role salt and water played in shaping planet Earth.

Professor Brian Cox concludes his exploration of our place in the universe by asking what next for the ape that went to space. Our future is far from certain. In Florida, Brian joins the latest efforts to protect Earth from potential catastrophic events. He joins a team of Nasa astronauts who are training for a future mission to an asteroid - should we ever discover one coming our way - under 30 feet of water in a submerged laboratory that simulates space. It is just one example of how, for our long-term survival, space exploration may well be vital. It is a view shared by Apollo 16 astronaut Charlie Duke, who tells Brian what it was like to escape the confines of the planet. It is a dream that both Nasa and now commercial companies share as they race to get humans back into deep space.
But space travel, like every leap our civilisation has ever made, requires energy. Here too, scientists are hard at work attempting to safeguard our future. At the National Ignition Facility in California, Brian witnesses the world's most successful fusion experiment in action. He believes that if their mission succeeds, our civilisation will have unlocked a way to the stars that will not destroy the planet in the process. Brian concludes by returning to the top of the world in Svalbard, where he gains access to our civilisation's greatest treasure, locked away in a vault buried deep in the permafrost.

One hundred years after Columbus' arrival in the Caribbean, Spanish Conquistadors and Priests, push into North America in search of gold and to spread Catholicism. With the arrival of the British in North America, the two colonial systems produce contrasting societies that come in conflict as Manifest Destiny pushes the U.S into the Mexican territories of the South West. As the Gold Rush floods California with settlers, complex and vital communities are overwhelmed. The elites, including Mariano Vallejo and Apolinaria Lorenzana lose their land. Mexicans and Mexican Americans are treated as second-class citizens, facing discrimination and racial violence. Resistance to this injustice appears in New Mexico as Las Gorras Blancas (The White Caps), burn Anglo ranches and cut through barbed wire to prevent Anglo encroachment. At the same time, New Mexicans manage to transform themselves through education, managing to preserve Hispano culture in New Mexico and their standing in the midst of an era of conquest and dispossession.

World War II is a watershed event for Latino Americans with hundreds of thousands of men and women serving in the armed forces, most fighting side by side with Anglos. In the Pacific, East L.A.'s Guy Gabaldon becomes a Marine Corp legend when he singlehandedly captures more enemy soldiers than anyone in US military history. But on the home front, discrimination is not dead: in 1943, Anglo servicemen battle hip young "Zoot suitors" in racially charged riots in southern California

In the 1960s and 1970s a generation of Mexican Americans, frustrated by persistent discrimination and poverty, find a new way forward, through social action and the building of a new "Chicano" identity. The movement is ignited when farm workers in the fields of California, led by Cesar Chavez and Dolores Huerta, march on Sacramento for equal pay and humane working conditions. Through plays, poetry and film, Luis Valdez and activist Corky Gonzalez create a new appreciation of the long history of Mexicans in the South West and the Mestizo roots of Mexican Americans. In Los Angeles, Sal Castro, a schoolteacher, leads the largest high school student walkout in American history, demanding that Chicano students be given the same educational opportunities as Anglos. In Texas, activists such as Jose Angel Gutierrez, create a new political party and change the rules of the electoral game. By the end of the 1970s Chicanos activism and identity have transformed what it means to be an American. Chicano and Latino studies are incorporated into school curriculum; Latinos are included in the political process.