The untold story of Sir Christopher Lee is set to be revealed in an upcoming documentary film.

When asked about his activities during World War II, Christopher Lee leaned into the interviewer, "Can you keep a secret?"

"Why, yes!", said the interviewer, hanging on his every word.

"Well, so can I!", replied Lee.

Sir Christopher Lee's military career is still shrouded in mystery.

The untold story of Sir Christopher Lee is set to be revealed in an upcoming documentary film.

The Life and Deaths of Christopher Lee features interviews with friends, family members and famous directors.

Jon Spira, from Headington, Oxford, had access to Lee's scrapbooks and 100 interviews from the British Film Institute's library.

The filmmaker tells the BBC the actor's life was an "incredible story" waiting to be told.

Lee starred in more than 250 films across eight decades, including the Hammer Horror, James Bond, Lord of the Rings, and Star Wars franchises.

But as Spira's film explains, he had a military career during World War Two still shrouded in mystery, and helped track down Nazi war criminals.

"Because he could speak fluently a range of different languages he got pulled into the secret service doing missions of which the facts have never fully come out," Spira explains.

"His cousin was Ian Fleming and a lot of people think the character of James Bond was based on him.

"He certainly didn't do anything to disavow people of that.

"You could almost do this as two films. That's why we called it The Life and Deaths of Christopher Lee, because his life is one story and his career is another."

Did you know that Sir Christopher Lee was...

1 Born into Italian aristocracy

2 A witness to the last public execution by guillotine

3 Introduced to Rasputin's assassins as a boy

4 A swordsman in an Errol Flynn film

5 The only person in the Lord of the Rings films to have met JRR Tolkien

6 An expert knife thrower

7 The oldest person to get on the Billboard music charts (with a Heavy Metal album)