The Hollow Choir is scripted by two writers new to Big Finish, the acclaimed horror and science fiction authors Helen Marshall and Malcolm Devlin.

Devlin said: "We were asked to write something horrible, because we both have experience writing horror stories. And so we thought about lots of things that upset us or scare us, and we thought of being stuck in caves. We were inspired by the graphic novelist Junji Ito, particularly The Enigma of the Amigara Fault, one of his most famous short pieces.

"Rhys is interesting to write for because he's actually just normal, he's an ordinary bloke, and putting ordinary people in extraordinary circumstances is more interesting than people who are special or magical. Rhys is vulnerable, and he's much more identifiable in that respect – he's John McClane in Die Hard 1 as opposed to John McClane in Die Hard 5!”

Co-writer Helen Marshall added: "With the cave setting, we were trying to play on that sense of intimacy that comes with a cramped, confined space. It gives us the chance to do something interesting in terms of the audio and the ambience – you put on your headphones and feel like you're in this really claustrophobic space. Combined with beautiful music, it’s quite creepy."

Olivia Forrest, Kai Owen, Simon Armstrong