Pan finds an illegal brain shop to uncover how the recordings have changed her.

An environmental thriller starring Pearl Mackie, Tanya Moodie and Pippa Haywood.

Theme music by Bonobo.

Written by Timothy X Atack.

Director: 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