Casualty is back from Saturday as it gears up for its 40th anniversary later this year – and the new 12-part series is looking explosive, to say the least. A trailer reveals two brand new characters and also shows some of the regulars yelling and crying, not to mention brawling and snogging – with one also being told that a baby is on the way.

In the video to tease the latest run of the BBC medical drama, Holby General and its residents are shown to be facing some of their biggest challenges yet. Many of them are also confronting personal demons while battling keep the trauma department open and some are also tasked with training a new generation of doctors.

Clinical lead Flynn Byron, played by former Call the Midwife star Olly Rix, seems to be on a collision course with shambolic Dylan Keogh. When Dylan is told to mentor new resident doctor Matty, played by Aron Julius, he point blank refuses leading Flynn to bellow: “Just suck it up and be his mentor for God’s sake!” This doesn’t seem to go well though, and results in full fisticuffs, with Dylan telling Flynn at another point: “It’s not about sides – this is a team.”

Meanwhile Jacob Masters (Charles Venn) looks to have continuing family dramas as he is heard to say “something’s got to change” while tearfully hugging close his wayward son Blake, watched by his young grandson Carter. Blake is also seen being marched away by the police.

Another shock moment is when Siobhan McKenzie (Melanie Hill) tells mum-of-three Faith Cadogan (Kirsty Mitchell) some big news. “You’re pregnant,” she announces, as the smile fades and colour drains from Faith’s face. Her relationship with Iain – actor Michael Stevenson – is under strain and she is heard to tell the former army corporal: “Find somebody else to fix.”

Another scene shows Siobhan telling the others: “We keep calm and we carry on”, before failing to follow her own advice and screaming with rage or frustration as others try to diffuse the situation.

As the ED is overwhelmed and the CQC (Care Quality Commission) closes in, Flynn and Siobhan must unite the team as tensions threaten to break it apart. Poor Rida Amaan, played by Sarah Seggars, is reduced to tears during an emergency. But at least things are going well for Cam (Barney Walsh) and Indie (Naomi Wakszlak), who happily share a kiss in the opening episode; Learning Curve.

The two new arrivals are in for a rocky ride. Matty is a charmer but isn’t impressed with some of what he sees, telling fellow new arrival Kim (Jasmine Bayes) that he’s making a complaint. “That’s not good enough,” he rages. “I’m reporting them to the CQC.”

And it’s not all plain sailing for confident Kim either, even though she declares: “I was made for the ED. You have no idea what I can do.” She’s soon being reprimanded with the words: “Part of being a doctor is doing the medicine – so do the medicine!” Jasmine said of her character: “The journey Kim goes on is far from simple, and I hope audiences are prepared to follow her into some troubled waters.”

Since making this series BBC Studios has won the tender to continue producing the Bafta-winning drama, which is made in Cardiff. Production on the next run starts in the spring.