The series is a re-examination of some of the under-reported and darkest parts of American modern history using little known documents and newly uncovered archival material, looking beyond official versions of events to the deeper causes and implications and exploring how events from the past still have resonant themes for the present day. This episode addresses the historical backround, consequences and reasons behind the use of atomic bombs against the Japanese in the second world war.

Eisenhower and the CIA played a great part in the shaping of the world in the 1950's; the development of the Cold war and the nerve-wrecking battle against communism, driven on by the U.S.

At 4.6 billion years old, the Solar System is our solid, secure home in the Universe. But how did it come to be? In this episode we trace the system's birth from a thin cloud of dust and gas. Shocked by a nearby supernova, the pull of gravity and natural rotation spun it into a flat disc from which the Sun and planets coalesced. It all happened in the space of 700 million years, during which the planets jockeyed for position, dodging the Late Heavy Bombardment of deadly asteroids and setting into the neat, stable system that we now realize might be a rarity in the universe.

David Attenborough concludes his epic history of the evolution of flight with an exploration of the highly advanced fliers that dominate our skies today – the extraordinarily diverse skills of the birds, and the sonar-guided precision of the bats. He encounters some of our planet’s most remarkable fliers – from peregrine falcons dive-bombing starlings over Rome, to hummingbirds hovering in the cloud forests of Ecuador. In a spectacular finale, he visits Gomantong cave in Borneo to witness the mass exodus of a million bats.

Every day of our lives, we are bombarded by thousands of different images, images which affect us in countless different ways. But of all these there's one particular kind of image whose power is uniquely mesmerising, because while it terrifies us somehow it also comforts. But although it can manipulate us, it also reassures, It's the image of death.

Sultan Mehmed II's siege of Constantinople enters its third week. Mehmed's artillery teams continue their relentless bombardment of Constantinople's walls. After his navy suffers a devastating defeat, Mehmed moves his ships overland to the Golden Horn in a daring, visionary feat. In the shadow of betrayal, Giustiniani attacks the Ottoman fleet.