Theia tells Pan the story of how the old world came to an end. An environmental thriller starring Pearl Mackie, Tanya Moodie & Pippa Haywood. With theme music by Bonobo. Written by Timothy X Atack and directed by Becky Ripley. Each episode comes with its own talk and soundscape. And you can take part in our interactive experiment to see how you respond to sounds of nature at: bbc.co.uk/forest #Forest404