The movie is to be directed by debutante Jasmeet Reen.
Sonakshi, known so far for her bubbly and effervescent characters, is all set to take a serious shot at an intense and real performance.
A source very close to the actress said: "Though no formal announcement has been made Sonakshi is playing Amrita Pritam. She is very excited about the challenge of playing her first real-life character."
This won't be Sonakshi's first realistic character. She earlier did Vikramaditya Motwane's "Lootera", for which she received appreciation.
"There are many reasons why Sonakshi does commercial films. Firstly, she enjoys them. And secondly, she can't say no to friends who want her in their films. But now she's determined to try her hand at something more serious," the source added.