Naomi Watts has signed on to play ballet legend Margot Fonteyn in Margot & Rudi, the new romantic drama from Mrs. Harris Goes to Paris director Anthony Fabian that is set in the world of Swinging Sixties ballet.

The film explores the iconic partnership between Fonteyn, a 42-year-old prima ballerina and Britain’s most famous dancer, and Rudolf Nureyev, the 23-year-old rebellious Soviet defector who became her partner on stage (and, it was rumored, off it as well).

Their explosive, undeniable on-stage chemistry sparked speculation, never confirmed and never fully denied, that their affection extended into their private lives. Fonteyn was married at the time, and Nureyev was openly gay, known for his long-term, volatile relationship with Danish dancer Erik Bruhn.

Alexandr Trush, principal dancer with the Hamburg Ballet, will play Nureyev. The Russian-speaking Ukrainian ballet star is known for his productions of Giselle and Romeo and Juliet, two iconic ballets that will also feature in the film.

“Growing up in Mexico City, watching Margot and Rudi’s performances in the cinema sparked my passion for stories that blend music, theater, and dance,” said Anthony Fabian. “Their love, defying barriers of culture, age, class, and sexuality, is romantic, unconventional, and thrilling—a love story like no other.”

Two-time Oscar-nominated Watts studied dance becoming an actress. The Mulholland Drive, 21 Grams and The Impossible star recently played Jackie Kennedy Onassis in FX’s Love Story and will be seen next alongside Luke Evans in The Housewife.

The Margot & Rudi cast includes Richard E. Grant (Can You Ever Forgive Me?), Demián Bichir (The Hateful Eight) and Harriet Walter (Succession). Fabian will direct from a script by Mrs. Harris Goes to Paris writer Olivia Hetreed.

Fabian will produce the film through his Elysian Films outfit, together with Hetreed at Sympathetic Ink, Mike Goodridge at Good Chaos and Chris Coen. Executive producers are Thom Mount, Jeffrey Berg and Andy Paterson.

WestEnd Films has boarded world sales on Margot & Rudi and will introduce the project to buyers at the Cannes film market next month.