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.