| Name | Character | Episodes |
|---|---|---|
| Jason Isaacs | Mark Brydon | 6 |
| Genevieve O'Reilly | Caroline Hanley | 6 |
| Christopher Bolton | Vinny Swain | 6 |
| Eva Birthistle | Jane Lavery | 6 |
| Lennie James | Luke Gardner | 6 |
| Ben Daniels | Nicholas Brocklehurst | 6 |
| Aaron Abrams | Matthew Weiss | 6 |
| Noam Jenkins | Christopher Styles | 6 |
| Sharon Gless | Lynne Warner | 6 |
| Ted Whittall | Gordon Adair | 6 |
| Marnie McPhail | George Blake | 6 |
| Patrick Garrow | Brad Godovsky | 4 |
| Kevin Hanchard | Boston FBI Agent | 1 |
| Nigel Bennett | 1 | |
| Alex Jennings | 1 | |
| Neil Pearson | 1 | |
| Michael Rhoades | Gary Pritchard | 1 |
| Joe Pingue | 0 | |
| Roman Podhora | 0 | |
| Anita Carey | 0 | |
| Lennie James | 0 | |
| Vijay Mehta | 0 | |
| Ron Lea | 0 | |
| David Huband | 0 | |
| David Eisner | 0 | |
| Wayne Downer | 0 |