The series consists of 30 episodes, which focus on the professional and personal lives of medical and ancillary staff at the emergency department (ED) of the fictional Holby City Hospital.
Sixteen regular cast members reprised their roles from the previous series and actor Michael Stevenson returned to the serial in episode fourteen as Iain Dean, a paramedic.
The series explores the impact of the pandemic on ED staff and to truthfully portray the topic, discussions about how political Casualty could become occurred with Tim Davie, the Director-General of the BBC.
[6] Kate Oates, the head of continuing drama at BBC Studios, expressed her delight at resuming filming and to returning to transmission.
As well as previewing new and continuing stories, the trailer revealed stunts featured in the series, including an exploded bomb and an ambulance crashing into a river.
[4] Preece told Sophie Dainty of Digital Spy that this was challenging as the show works on "close contact medicine, stunts and emotional exchanges", which was hard to film while adhering to physical distancing measures.
To avoid using NHS resources, Casualty sourced their PPE from an alternative supplier and despite this, it maintains effectiveness, allowing them to occasionally breach the physical distancing measures.
[14][2] Series 35 explores the impact of the COVID-19 pandemic on staff in emergency departments, maintaining the drama's tradition of "[reflecting] the difficult realities of the NHS".
She commented, "Hopefully, on shows like ours, we can make those social points at the same time as our heroes are seen in their best Avengers style embracing the same kind of life-or-death situations they always have.
The episode is billed as "one of [Casualty's] most powerful episodes to date" and explores clinical lead Connie Beauchamp (Amanda Mealing) managing the department with support from senior nurses Jacob Masters (Charles Venn) and Charlie Fairhead (Derek Thompson), consultant Will Noble (Jack Nolan) becoming disillusioned with the NHS, and paramedic Fenisha Khatri (Olivia D'Lima) trying to protect her unborn baby.
Preece noted that this allows Casualty to continue exploring stories including Fenisha's pregnancy, a love triangle between Dylan Keogh (William Beck), Faith Cadogan (Kirsty Mitchell) and Lev Malinovsky (Uriel Emil), and Connie and Jacob's romance.
[2] She added that writers wanted to explore the complications of Fenisha's pregnancy due to the baby's father, Ethan Hardy (George Rainsford), having Huntington's disease.
[2] Other stories further explored from the previous series are Charlie's grief, following the death of his wife, and nurse Jade Lovall's (Gabriella Leon) deafness.
One story focuses on "new territory" for paramedic Jan Jenning (Di Botcher) and her police officer wife Ffion Morgan (Stirling Gallacher).
He explained that the episode would include stunts and described it as "one of those big Casualty ensemble pieces with an event which pulls together lots of the cast".
William Beck appears as Dylan Keogh, a consultant in emergency medicine, while Di Botcher portrays Jan Jenning, the operational duty manager at Holby Ambulance Service.
[1] Olivia D'Lima stars as Fenisha Khatri, a paramedic, and Jason Durr features as David Hide, a senior staff nurse.
[4] Uriel Emil plays paramedic Lev Malinovsky,[1] and Amanda Henderson appears as staff nurse Robyn Miller.
[7] Shaheen Jafargholi and Gabriella Leon reprise their roles as staff nurses Marty Kirkby and Jade Lovall, respectively.
[13] Tony Marshall features as Noel Garcia, a receptionist,[7] and Amanda Mealing portrays Connie Beauchamp, the department's clinical lead and a consultant in emergency medicine.
[1] Kirsty Mitchell stars as Faith Cadogan, an advanced clinical practitioner (ACP),[4] and Neet Mohan appears as Rash Masum, a F1 doctor.
[1] Additionally, three cast members feature in a recurring capacity: Harry Collett appears as Oliver Hide, the son of David,[23] Stirling Gallacher plays Ffion Morgan, a police officer,[24] and Jacey Sallés portrays Rosa Cadenas, a healthcare assistant.
Preece called Marshall, who has appeared in the show since 2008, "a much loved member of the behind-the-scenes Casualty family" and expressed her sadness at the character's death.
Deborah Sathe, the senior head of content production at BBC Studios, praised Connie and Mealing, in particular for her work following the show's return to filming.
[29] On 17 December 2020, it was announced that actor Michael Stevenson had reprised his role as paramedic Iain Dean, following his departure in the previous series.
[36] After a guest stint in the previous series, actress Adele James returned in episode five as Tina Mollett, an agency nurse.
It was announced on 3 February 2020 that Chris Gordon would reprise his role as Ross West, the son of Jan, as part of "a huge and terrifying story" involving the character and Ffion.
She added that her character would appear with Jan.[2] Lollie McKenzie reprised her guest role as Natalia Malinovsky, the daughter of Faith and Lev, in episode two.
[48] Kriss Dosanjh reprises his role in episode 13 as Rash's father, Ashok Masum;[49] he previously appeared in series 34.
[50] Graham returns in the fifteenth episode, alongside Marty's mother, Bibi Kirkby, who is portrayed by Fisun Burgess.