BBC medical favourite Casualty is celebrating its 40th anniversary with a dramatic two-part special, echoing the gas-explosion opening of its first episode in 1986
The long-running series has followed patients and NHS staff through emergencies, scandals and social issues, while helping launch the careers of several major British actors
Its anniversary storyline features a suspected terrorist attack, a dangerous rescue and an ambulance submerged underwater
The programme will also enter a new era, moving its fictional setting from Holby to Cardiff for the next series
The specials air on Saturday at 8pm on BBC One and BBC iPlayer.