The series began with 15 roles receiving star billing. Amanda Mealing portrayed Connie Beauchamp, a consultant on the cardiothoracic surgery ward, Darwin. Paul Bradley played Elliot Hope, also a cardiothoracic consultant, and Luke Roberts played Joseph Byrne, a registrar on Elliot's firm. Hari Dhillon played consultant general surgeon and Director of Surgery Michael Spence. Hugh Quarshie acted as Ric Griffin, also a consultant on the general surgery ward, Keller. Rosie Marcel portrayed Jac Naylor, a general surgical registrar. Emma Catherwood and James Anderson appeared as Penny and Oliver Valentine, siblings and F1 doctors. Duncan Pow played Linden Cullen, a consultant on the hospital's Acute Assessment Unit. Robert Powell played Mark Williams, the unit's consultant nurse, and Tina Hobley played his daughter, ward sister Chrissie Williams. Patsy Kensit and Rebecca Grant played ward sisters Faye Byrne and Daisha Anderson, and Jaye Jacobs and Phoebe Thomas played staff nurses Donna Jackson and Maria Kendall.
