'The Help' star Jessica Chastain to play Princess Di

"Tree of Life" and "The Help" actress Jessica Chastain has been cast as the late Diana, Princess of Wales, in the upcoming film "Caught in Flight," IndieWire reported.

The thespian, 30, will play William and Harry's late mom in a film about Diana's alleged secret affair with heart surgeon Dr. Hasnat Khan, said to be the love of her life.

The flick will be directed by German director Oliver Hirschbiegel and is set to begin filming in Pakistan, Angola, the South of France and Paris in March. Rumor has it Keira Knightley was also considered for the role. Diana died at age 36 in a car crash in 1997.

Follow Style/Buzz/Special Sections Editor Perrie Samotin on Twitter: @PerrieWS