| Name | Character | Episodes |
|---|---|---|
| Ben Miller | Detective Superintendent Richard Groves | 16 |
| Anne-Marie Duff | Dr Susannah Newman | 16 |
| Sam Heughan | Ryan | 8 |
| Joely Richardson | Jackie Snowden | 8 |
| Eddie Marsan | Alistair Underwood | 8 |
| Antonia Thomas | Maia | 8 |
| Gina McKee | Kate | 8 |
| Dominic Cooper | Jon Fallow | 8 |
| Richard E. Grant | Harry | 8 |
| Tamsin Greig | Natasha Groves | 8 |
| James Nesbitt | Danny Frater | 8 |
| Niamh Algar | Nicola | 8 |
| Sacha Dhawan | Jaisal | 8 |
| Imogen King | Christina | 8 |
| Vinette Robinson | Lousia McAdams | 8 |
| Celine Buckens | Sapphire | 8 |
| Nicholas Pinnock | Joseph Buckley | 8 |