"Promise" is the 998th episode of Holby City and the 43rd episode of the 21st series. It was preceded by "Hope Is a Powerful Drug" and followed by "Hubble Bubble". The episode was directed by Griff Rowland and written by Patrick Homes.
This episode features guest appearances by Patricia Potter and Daon Broni as consultant general surgeon Diane Lloyd and Ric Griffin's deceased son Leo. A former main cast member, Potter last appeared on the show in June 2007 after her character was killed off.
- Hugh Quarshie as Ric Griffin
- Jo Martin as Max McGerry
- Catherine Russell as Serena Campbell
- Lee Mead as Ben "Lofty" Chiltern
- David Ames as Dominic Copeland
- Bob Barrett as Sacha Levy
- Jaye Jacobs as Donna Jackson
- Nic Jackman as Cameron Dunn
- Marcus Griffiths as Xavier "Zav" Duval
- Rosie Marcel as Jac Naylor
- Verity Marshall as Helen Pidge
- Daon Broni as Leo Griffin
- Patricia Potter as Diane Lloyd
- Leah Mondesir-Simmonds as Erika Johnstone