A new BBC drama that looks at what would have happened if the Nazis had won the Battle of Britain will send a chill down viewers' spines, its writers have said.
SS-GB, which stars Sam Riley and Kate Bosworth, will look at life in Nazi-occupied London and will highlight how close the British were to losing the war.
Writers Neal Purvis and Robert Wade, the Bafta winners behind Bond films Spectre, Skyfall and Casino Royale, adapted Len Deighton's 1978 alternate history book of the same name.
Wade said: "It constantly makes you think: 'What would I have done?' This example of alternate history is particularly interesting because it's so close to what might have happened."
He added: "In SS-GB, the British are living through the Occupation. The game is still not over. History is alive – and that's what's particularly clever about this story.
"It's very important that we talk about this stuff. It's become part of our mythology that we stood alone. We did, but it was a very close-run thing."
Purvis found one moment particularly chilling on set, saying: "Seeing Lars Eidinger, who plays SS officer Standartenfuhrer Oskar Huth, coming into a church to arrest someone – that was properly scary.
"Watching a man in an SS outfit with that distinctive long leather coat really brings it home. Even though we know they're actors and are just pretending, just seeing a high-ranking SS officer inside a British church is really chilling."
Wade added: "We could have lost the Battle of Britain if the weather had been different. In fact, it was miraculous that we won that battle.
"Britain was alone at that period. America wasn't involved. They were looking the other way. It was before Pearl Harbour.
"Winston Churchill's great objective was to bring the Americans into the war, but for a long time he couldn't do it.
"In 1941, Churchill wasn't popular, although he's been borne out by history. So SS-GB has a sophisticated plot because as well as concentrating on a murder, it's also about how we got the Americans to commit to the war.
Riley who plays Douglas Archer, a British detective working under the SS, said the trip back to the 1940s was particularly appealing. He said: "For a start, I'd never played a detective before, especially one in a trilby, smoking cigarettes!"
He added: "I was also attracted by the fact that Archer speaks German, and I've been living in Berlin for the last eight years.
"As my dad and my agent put it: 'People might actually watch this!'"
Bosworth, who plays New York Times journalist Barbara Barga, added: "The sense of 'What if this had happened?' is gripping.
"We know the history; we know that type of tragedy, but what if history had taken a slight turn?"
"I've always wanted to play a character from the 1940s. The look was very appealing to me. The physicality, the wardrobe, the hair and the make-up..."
:: SS-GB begins on BBC One at 9pm on February 19.