| | Breslin | Detective on the Murder Squad |
| Antoinette | Conway | Detective on the Murder Squad |
| | Cooper | Pathologist |
| | Costello | Senior detective in the squad for the first
few months of Antoinette's assignment |
| Louis | Crowley | Aggressive journalist for The Courier |
| J.P. | Dooley | Garda on duty at the murder scene |
| Rory | Fallon | Aislinn's prospective date for evening of murder, owner of a book-shop |
| Laurence | Flannery | Friend of Lucy's, published a theater history book |
| | Healy | Murder squad detective |
| | Kellegher & Reilly | "Floaters," cops who checked CCTV footage & escorted Rory back home |
| | King | Murder squad detective |
| Joe | McCann | Murder squad detective |
| | Meehan & Gaffney | "Floaters," cops who carried out the door-to-door investigation of the case |
| Sophie | Miller | Lead crime scene tech |
| Stephen | Moran | Antoinette's partner on the Murder Squad, aka Steve |
| Aislinn | Murray | Murder victim, trendy young woman;
receptionist at cleaning services company, aka Ash |
| Desmond Joseph | Murray | Aislinn's father who disappeared in 1998 |
| Mrs. | Murray | Aislinn's mother, emotionally unstable from desertion by her husband, now deceased |
| | O'Gorman | Murder squad detective |
| | O'Neill | Murder squad detective |
| Gary | O'Rourke | Cop in Missing Persons division, friend of Antoinette |
| Vanessa | O'Shaughnessy | Nurse who used Desmond's taxi service, emigrated to England |
| | O"Kelly | Superintendent of the Murder Squad |
| | Quigley | Murder squad detective |
| Lucy | Riordan | Aislinn's good friend |
| | Roche | Murder squad detective |
| | Stanton & Deasy | "Floaters," cops who brought in a witness |
| | Winters | Murder squad detective |
| Bernadette | | Administrative assistant for the squad |
| Fleas | | Undercover cop, friend of Antoinette from training school |
| Goggles | | Criminal, former informant for Fleas, incarcerated for drug trafficking |
