Competition to win a partner …has created some of the most extraordinary beauty and life-threatening violence anywhere in nature. Dazzling colours, elaborate dances and powerful weapons have all evolved to attract and defend a mate. The stakes could not be higher: without a mate, the journey of life ends here... sometimes literally.

Researchers discuss mythic ancient treasure and curses including King Solomon's Ring, lost Aztec treasure, and the Omphalos.

Brian asks how, from a lifeless cosmos, it is possible that a planet can produce the more than eight million species we know of.

Brian explores the physics of the size of life through some close encounters with Australia's wildlife. From swimming with great white sharks to tracking red kangaroos, he discovers that the size you are profoundly affects the life you lead and, ultimately, how long you have to enjoy it.

This episode examines the end of and the period immediately after World War II. It looks at Stalin's efforts to seize control of Poland and Eastern Europe, Democratic part bosses efforts to drop Henry Wallace from the 1944 presidential ticket, and British efforts to maintain their colonial holdings after the war.

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.