Carey Mulligan was terrified she would "kill" Ralph Fiennes.
The pair star together in new movie 'The Dig' and when the 57-year-old actor was entombed in dirt for one scene in the film, his 35-year-old co-star had to scrabble through the earth with her bare hands to free him, and the actress admitted it was the "most terrifying" shoot she'd ever done.
She told the Daily Mail newspaper's Baz Bamigboye: "It was the most terrifying moment of my career!
"I was responsible for getting the soil away from his face. As the cameras came down, all I could think was, 'Don't let me kill Ralph Fiennes!' "
The movie is an adaptation of John Preston's historical novel, a fictionalised account of the 1939 excavation at Suttoon Hoo in Suffolk, where self-taught archaeologist Basil Brown (Fiennes) discovered the royal burial ship of an Anglo-Saxon king.
And director Simon Stone wanted the scenes to be as realistic as possible, so set dressers would hide artefacts around the site before each take.
Carey said: "So the guys digging up treasure were really digging up treasure.
"When they found them, the camera would capture their genuine reaction."
Carey had to "age up" to play Edith Pretty, who hired Brown, in the movie and joked it was an "ego bash".
She said: "They would make me scrunch up my forehead and my eyes and very delicately paint in some more lines. It was, you know, an ego bash.
"Not fun to look in the mirror, but a fun part of the prep."
For Ralph's look, he sported dirt-caked fingernails and hair and make-up designer Jenny Shircore ordered him not to trim his ear hair.
She said: "I wouldn't let him cut it!"
Ralph added: "That's right."
Both stars were impressed by the platonic relationship between their characters.
Carey said: "It's so unusual to see a female and a male character on screen where the relationship is just about a meeting of the minds — and the mounds! — and that can be really profound.
"It doesn't need to be a romantic connection."
Ralph added: "Edith and Basil had a common understanding about the dig, the ship, and what the past means. It's full of symbolism. It's the history of England, in the earth.
'A king, coming out of the ground in 1939, when the whole sense of the nation's identity is being crystallised by war approaching."