Horizon puts Graham Hancock's controversial theories about the past to the test, dissecting his evidence for a lost civilisation.

Although scientists believe they have categorically disproved the myth of Atlantis, the idea is more popular now than ever before. The latest exponent of the theory of a single lost source for all civilisation, is Graham Hancock. Although he doesn't call it Atlantis, his compelling ideas about a sophisticated society destroyed in a flood 12,000 years ago seem to be based on a reworking of the original Atlantis myth, whose survivors brought culture, religion, monument-building and civilisation to the rest of the world.

Orion's BeltGraham Hancock offers various pieces of evidence to support his theory. He claims that the mysterious lost civilisation left its mark in ancient monuments, which he calculates were built to mirror certain constellations of stars. His hugely popular ideas have attracted such a wide audience that they stand to replace the conventional view of the past, which is based on scientific evidence that the civilisations of the ancient world were developed independently, by different peoples, on different continents.

Horizon journeys across the world to examine Hancock's evidence for a lost civilisation and puts his theory to the test.