The Lyell are called to King's Cross Station Museum, where they discover the bodies of eight victims entombed below. With the knowledge that a prolific serial killer was operating in London nearly 20 years ago, Nikki and the team know this will be a case like no other.
| Name | Type | Role | |
|---|---|---|---|
| Ed Whitmore | Writer | ||
| Sharon Rose | Guest Star | DC Chloe Abbott | |
| Neil Pearson | Guest Star | DI Steve Tudor | |
| Mark Oosterveen | Guest Star | Newscaster | |
| Steve Nicolson | Guest Star | Keith Pryor | |
| Monika Miles | Guest Star | Anna Górska | |
| George Watkins | Guest Star | Carl Streeting | |
| Jude Akuwudike | Guest Star | Malcolm Jones | |
| Colin Stinton | Guest Star | Ted Holmes | |
| Ellen Thomas | Guest Star | Esther Daniels | |
| Lisa Allen | Guest Star | Tourist | |
| Rupert Holliday Evans | Guest Star | Russell Drake | |
| Hermione Norris | Guest Star | CS Sheila Court | |
| Hayley Carmichael | Guest Star | Joanne Perry | |
| Michele Winstanley | Guest Star | Barbara Apstead | |
| Toby Frow | Director |