Romola Garai has revealed David Nicholls book One Day "destroyed" her because the ending was so sad.
The 29-year-old actress - who stars as producer Bel in BBC show The Hour - appears alongside Anne Hathaway and Jim Sturgess in the new film adaptation of the hit novel.
Romola said: "It's an amazing novel. I cried! I was destroyed at the end!"
She went on: "A friend of mine finished it at 3 in the morning. She rang me at 7. I was like 'I'm an out-of-work actor. Why are you ringing me at 7 in the morning?' And she was like 'I've been awake since 3 o'clock and it's really got me.' Very sad."
The Atonement star also plays a drug addict in new film Junkhearts and after becoming so well known for playing period roles she is pleased to have been cast in something more contemporary.
Romola said: "I would like to do more contemporary films.
"I think it's difficult... I'm not moaning. I don't want to sound like I'm complaining - I'm so lucky.
"But you can't get away from the way you've been perceived and defined as a star. It's a pointless exercise. The point of being a movie star is that people cast you in a role. Actors tie themselves in knots trying to get out of that.
"The only thing you can want from it as a job is as much diversity as possible. If you have the opportunity as an actor to control your career in any way, then you've won the jackpot. It's not a job with any control at the best of times."
:: Romola stars in The Hour which is available now on BBC DVD and iTunes.