The disappearance and fate of the tomb of Alexander the Great in Alexandria is among the most momentous and tantalising of all the mysteries we have inherited from the ancient world. Generations of scholars and historians have succumbed to the allure of the quest.
Now archaeologist Pepi Papakosta is on a mission to find Alexander the Great's lost tomb. Excavating in a public garden in the center of Alexandria, Egypt, the city he founded 2,300 years ago, she has discovered a rare marble statue of Alexander, Greek treasures and secret tunnels. But Pepi's biggest find is an extraordinary discovery even she was not expecting.

The film explores the life and the mystery surrounding the death of American actress and cultural icon Marilyn Monroe through archival footage and previously unheard interviews with her inner circle. The filmmaker Anthony Summers spent three years collecting 650 tapes recorded with people who either knew Monroe in her lifetime or had knowledge concerning her death.

The documentary reveals the hidden power of sound in film and in our lives through interviews, film clips and a look at its actual process of creation and discovery. It captures the history, impact and creative process of this art form with insightful, poignant and entertaining stories told by legendary sound designers and visionary directors, and the sound artists they collaborate with who create the magic in all the films we love.

A guide to plants that thrive in human-dominated environments, including trees that grow across canyons in India, which have developed into living bridges. The programme examines the origins of growing crops and the ongoing influence on the world of wild plants, as well as efforts to preserve species, from snipers firing pesticide bullets from helicopters to fend off invasive plants to plants being painstakingly pollinated using a paintbrush.

The fascinating history of the military force of the Soviet Union. For 70 years, the Red Army was one of the foundations of the USSR, an instrument of fear as well as admiration, a symbol of liberation as well as coercion. While everyone knows that Trotsky's name is attached to its creation, most of its past is made up of military defeats and failures, contrary to the common idea. This documentary explores its history, combining epic narrative and deconstruction of the myth.

Plants that have developed to thrive in the desert, including cacti that grow in the shade of other trees and collect water in pleated trunks that expand and contract - but can also find themselves a host to other plants, like desert mistletoe. This programme also reveals how tobacco plants being eaten by caterpillars are able to summon the creatures' natural predators, and how tumbleweeds roll across the landscape, only unfurling and growing when they encounter rain.