Richard Armitage wants his Red Eye character to be an "enigma"

He insists that he is innocent, but is nevertheless extradited to face justice, with DC Hana Li (Jing Lusi) as his police escort.

But when catastrophe strikes on their flight back to China, it becomes clear that there's more to this case than anyone imagined.

Speaking to RadioTimes.com, Armitage explained: "One of the things that I was attracted to about the role was, by default, as a doctor, he's somebody that we should trust. He's taken the Hippocratic Oath to do no harm.

"So, therefore, the accusation of killing someone and leaving them for dead strikes me as unfair."

On his first reading of the scripts by Peter A Dowling (Flightplan), the Fool Me Once star said he was kept guessing regarding his character's true intentions – with a forgotten period of time being central to the mystery.

"I don't know if he's who he says he is," recalled Armitage. "What happened to him in Beijing? He can remember part of it. There's another part of it that he has no memory of which, when you're faced with a legal challenge, is really difficult territory.

"So, he's already on thin ice... protesting his innocence, but really not being sure himself."

The actor is known for carefully analysing his characters, and even devising thorough backstories for them, but in this case he wanted Dr Nolan's past to remain a mystery even to him.

"I just thought, actually, it becomes a more enigmatic tool," he explained. "Normally, I would probably have written a biography of him, but I didn't. I focused on his job and I focused on the here and now, because I wanted this man to be an enigma."

Armitage added: "I did like the idea of the viewer fluctuating between completely trusting him and really having serious doubts about who he really is."

Red Eye premieres on ITV1 at 9pm on Sunday 21st April. Stream all episodes on ITVX after episode 1 airs.

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