The Oscar-nominated Up in the Air actress told Movieline that she has asked director Duncan Jones on several occasions to reveal the ultimate fate of Jake Gyllenhaal's soldier Colter Stevens, who enters alternate realities in order to uncover the identity of a terrorist on a commuter train.
Farmiga portrays Colleen Goodwin, an Air Force officer who helps Stevens navigate through the various 'source codes'.
She said: "[Duncan] says that it's a Choose Your Own Adventure novel, of sorts, is the way I've been expressing it. That's certainly what drew me. I feel like every reality is a viable reality and it's basically which one you choose - whichever ending you think is most fulfilling for yourself.
"It is ambiguous, but pointedly so, I think. Because it's all theory and philosophy and if anything was absolute then we would have a tidy answer But I think the ambiguity works. Duncan will say that all the realities that he's been in are true."
Source Code is currently sitting in second place at the UK and US box office behind Russell Brand's Hop.
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Watch the first five minutes of Source Code below: