Elle Fanning, Naomi Watts and Susan Sarandon have been cast in 'Three Generations'.

The new film - written by Nikole Beckwith - will focus on a teenager (played by Fanning) in New York who makes the transition from being a man to a woman, and her single mother (Watts), who struggles to come to terms with having to raise her child.

Elle Fanning

The struggle of the daughter runs parallel to the story of her lesbian grandmother, played by Sarandon, who can't fathom her granddaughter's life-changing decision, according to The Hollywood Reporter.

Sarandon's character is also left feeling confused by her on-screen daughter's refusal to move away from her childhood home.

Fanning, 16, appeared alongside Hollywood superstar Angelina Jolie in 'Maleficent', while she's also set to star in 'Trumbo' with 'Breaking Bad' actor Bryan Cranston.

Watts is currently filming 'Demolition', while co-star Sarandon is best known for her Oscar-winning performance in the 1995 movie 'Dead Man Walking', which also featured acting icon Sean Penn.

'On a Clear Day' director Gaby Dellal is set to helm the project, with production due to begin in New York early next month.