As the action begins, a seriously ill man has been choppered in from a road accident. Vascular surgery specialist Lorraine Rappaport sets to work on the patient - but when office politics come into play, she is asked to step down, forcing hospital fellow Fiona Lomas to take over. But it soon becomes clear that she doesn't have the theatre experience of her colleague.
Consultant Glen Boyle takes control when a woman is brought in with a fence post impaled through her face - and insists on opening up the patient when she starts haemorrhaging, uncovering a heart-wrenching explanation for the injuries. Amid all the action, Fiona struggles to deal with the fact that she's working with her ex once again.
The team sets to work on a badly beaten man covered from head to toe in lesions and lacerations - and interests are piqued by the discovery of a serial number branded on the patient's arm, suggesting he may be a slave labourer or a victim of trafficking. However, as the man's temperature soars, the doctors realise they may be dealing with a dangerous, and highly infectious, disease - and the trauma centre is forced into lockdown.