Casualty actor William Beck has described leading the audience through the show's 40th anniversary special as a "real privilege".
The BBC medical drama, recognised as the world's longest-running show of its kind, will mark the milestone in September with a two-part story.
The special will feature a "high-stakes major incident" that throws Holby City Hospital into chaos. Beck's character, Dylan Keogh, battles personal tragedy while guiding his team through their darkest hour, according to the BBC.
Beck on the anniversary special
Beck said: "Seeing how people respond under pressure can take you by surprise.
"The opportunity to give people something that feels authentic and recognisable but also surprises them – that's gold dust in TV.
"With Dylan, there's a real opportunity to explore what happens when the person everyone relies on is pushed to his limits.
"I know it's been said that Dylan doesn't like the responsibility of leading the department, but I think he does.
"It's a lovely opportunity, and a real privilege, to lead the audience through this story – particularly for the 40th anniversary. It really is pinch-yourself stuff."
He added that the special would be "entertaining as well as traumatic", placing his character at its centre "in a way that he hasn't been before".
Why the show has endured
Reflecting on Casualty's longevity, Beck suggested audiences enjoy the show because they appreciate the NHS.
He said: "It's a unique environment. The emergency department is somewhere that we all have experience of, most frequently when we really don't want it.
"We're thrown in with people who are entirely at random, which is such an amazing environment to make a drama.
"People recognise it and have sympathy for those who work there and for the people being treated there.
"It's also something that we know we're lucky to have, and we continue to fight for.
"My parents both worked for the NHS and are avid supporters of it, but it didn't make them, or me, blind to the huge difficulties that it faces. Everybody recognises that."
History and broadcast details
The Bafta-winning show first launched in 1986 and led to the hit spin-off Holby City, set in the same fictional location in south-west England.
Filmed at Cardiff's BBC Roath Lock Studios since 2011, the show is also expected to move to a new fictional hospital in Wales next year.
Both parts of Casualty's 40th anniversary special will air on September 5 on BBC One starting at 8pm.
