CH4 - Mysteries of... (2025)

Explores places with a mysterious past through a combination of history, archaeology and mythology.

Part 1: Stonehenge
Takes an extensive look at the site's origins, from tales of Merlin to African giants in Ireland, and traces how prehistoric peoples harnessed the power of the sun to make profound statements about the cycle of life and death. It also explores the recent revelation that one of the sacred stones may have originated over 1000 kilometres away on Orkney.

Part 2: Loch Ness
Explores the enduring history, folklore and science of the Loch Ness monster, with contributions from believers, sceptics, tourists and locals. A passionate Nessie hunter believes he has the first audio recording of the monster, while an academic who considers the psychology behind these strange sightings. Plus, a look at similar legends from around the world.

Part 3: Sinkholes
Explores the history of sinkholes, examining incidents throughout history from high in the mountains of south west China to hundreds of metres underwater in the Gulf of Mexico. Cutting-edge technology reveals living environments deep within sinkholes. Cavers and divers pursue archaeological expeditions 80 metres deep, unearthing hidden worlds dating from ancient Rome and the Maya civilisation.