Former UNIT luminary Liz Shaw and her assistant Lou Bayliss are investigating a series of bizarre murders, all committed near a soon-to-be-closed psychiatric hospital. When the hospital is unexpectedly reprieved by rich Industrialist Peter Russell events seem to move out of Liz's control. Are the incumbent director of the clinic, Doctor Dove and his predecessor Doctor O'Kane harbouring the killer? What is the centuries-old horror hidden in the grounds? And what exactly is the secret of room zero?
| Name | Type | Role | |
|---|---|---|---|
| Mark Gatiss | Writer | ||
| Mark Gatiss | Guest Star | ||
| Sophie Aldred | Guest Star | ||
| Jon Pertwee | Guest Star | ||
| Linda Lusardi | Guest Star | ||
| Nicola Fulljames | Guest Star | ||
| Simon Messingham | Guest Star | ||
| Patricia Merrick | Guest Star | ||
| Colin Baker | Guest Star | ||
| Alexander Kirk | Guest Star | ||
| Jonathan Rigby | Guest Star | ||
| David Terence | Guest Star | ||
| Bill Baggs | Guest Star | ||
| Sylvester McCoy | Guest Star | ||
| Daniel Mills | Guest Star | ||
| Bill Baggs | Director |