Marion Cotillard has said her Rust And Bone character was an enigma to her.
The Oscar-winning actress plays paraplegic whale trainer Stephanie in the French drama, directed by acclaimed filmmaker Jacques Audiard.
She told Collider: "I had to solve a mystery because when I read the script she was a huge mystery to me, I didn't get right away who she was but I realised also that I didn't have to solve the whole mystery.
"When we started shooting I realised that I hadn't solved the whole mystery and I was a little worried about that but then I found that it was part of her, I didn't need to solve it."
Marion - who has been tipped to pick up an Oscar nomination for her performance - didn't have long to rehearse for the role because of her busy filming schedule.
"It's always different. Sometimes I need to prepare a lot, sometimes I need to leave this unknown space, so it's different each time. With this one we didn't have a lot of time to work with Jacques, when usually he really works a lot with actors, and we thought that we would do it with what we had," she explained.
"That was a great experience."