| Dr. Nathaniel Grant is a pioneering organ-transplant surgeon who takes risks that other doctors would not in order to save the lives of his patients. He works closely with his ex-wife, Kate Armstrong, an organ-donor coordinator with whom he has a volatile relationship. Grant's arrogance and willingness to perform risky procedures causes him to butt heads with the hospital administration. But his main focus is on his intense relationship with his job and his patients, often at the expense of his family. |
| Name | Character | Episodes |
|---|---|---|
| Morena Baccarin | Nurse Jessica Kivala | 10 |
| Kari Matchett | Kate Armstrong | 10 |
| Rockmond Dunbar | 10 | |
| Treat Williams | 10 | |
| Danielle Nicolet | 10 | |
| Dabney Coleman | 10 | |
| Gage Golightly | 10 | |
| Chris William Martin | 10 | |
| Melinda Dillon | 3 | |
| Mark Harelik | 2 | |
| Ashley Johnson | 1 | |
| Ryan Hurst | 1 | |
| Kay Lenz | 1 | |
| Tim Haldeman | 1 | |
| Patrick J. Adams | 1 | |
| Michelle Joyner | 1 | |
| Cynthia Ettinger | 1 | |
| Brandon Scott | 1 | |
| Henry G. Sanders | 1 | |
| Alec Mapa | 1 | |
| Todd Waring | 1 | |
| Sundra Oakley | 1 | |
| Bernard White | 1 | |
| John Benjamin Hickey | 1 | |
| Elizabeth Ruscio | 1 | |
| Ron Bottitta | 1 | |
| Jordi Caballero | August Pena | 1 |
| Ali Hillis | 1 | |
| Joe D'Angerio | 1 | |
| Benjamin John Parrillo | 1 | |
| Peter Choi | Hui Chan | 1 |
| Harry Johnson | Warden Victor | 1 |
| Rosemary Alexander | Helen Crawford | 1 |
| Elaine Mani Lee | Uterine Donor | 1 |
| Rachel Seiferth | Eleanora / Karen Snow | 1 |