Dr Ethan Hardy falls for a mysterious woman and soon finds himself embroiled in a murder case, as George Rainsford reveals…

This week’s standalone episode of Casualty is very different to what we see normally. How would you describe it?

“At its heart, it’s still Casualty but with a twist. There’s a voiceover and we used rain machines and lots of silhouette lighting. It’s very film noir.”

Your character, Dr Ethan Hardy, is working the night shift in the ED when patient Clyde (ex-Hollyoaks star Stuart Manning) is admitted. What’s happened to him?

“Clyde has a gunshot wound and, to Ethan, it looks like a suspicious suicide. Ethan then spots Clyde’s girlfriend, Bonnie, and a series of flashbacks reveal Ethan already knows her from the time she came to the ED with injuries and he discovered she was a victim of domestic violence at the hands of Clyde.”

Back then, why is Ethan so drawn to Bonnie (Renee Castle)?

“Ethan’s fascinated by her. Bonnie’s this very mysterious, intriguing character; she first comes into the ED wearing high heels and red lipstick and has a real aura about her. She’s a real femme fatale.”

Ethan’s a very by-the-book doctor. Does Bonnie impact on how he’s able to do his job?

“Absolutely! Bonnie makes him act quite differently in that he almost loses himself in this woman, rather publicly in the hospital – and in front of his brother, Cal! He’s quite gushing about her.”

And how does Ethan and Bonnie’s friendship develop from there?

“As Bonnie returns to the ED several times with different injuries, Ethan takes Bonnie under his wing and they become quite close.”

Does Bonnie want Ethan’s help?

“Well, at first she tells him to keep his nose out. But, really, she’s toying with Ethan and gives him just enough information because she is looking for a way out of her life. Then, Ethan suggests that Bonnie needs to take drastic action to save herself.”

Do those words come back to haunt Ethan?

“Yes! Back in the present, when Ethan sees Clyde with the gunshot wound and DNR (Do Not Resuscitate) tattooed on his chest, he thinks it’s something a little more sinister and suspects Bonnie shot him. Ethan also fears that, by effectively pushing her in that direction, he’s implicated himself. When Bonnie becomes aware Ethan’s onto her, she poisons him!”

Luckily, Ethan eventually comes round and, when Clyde dies, Ethan goes to the police to report a murder. Why is he so determined to do the right thing?

“Ethan’s a very genuine, honourable person and he feels incredibly guilty that he’s somehow involved in this case – it’s like he’s unwittingly become an accomplice when all he tried to be was Bonnie’s confidant and offer support. He thinks his only way out is to make sure he seeks justice for what’s happened – though I’m not sure he feels the police will believe him…”

Does this episode shape what’s to come for Ethan?

“Well, because of what happens with Bonnie, Ethan develops a real mistrust of the opposite sex. I really enjoy playing Ethan as a doctor but I definitely want to explore his love life more and also where his dark side might be!”

Casualty continues Saturdays on BBC1.