Rooney and Kate Mara Learned to Speak in Unison for Werner Herzog's 'Bucking Fastard' — and It Came Naturally

Sisters Rooney and Kate Mara spent their childhood playing together. That turned out to be all the preparation they needed for the strangest acting challenge of their careers: speaking the same words at the same time, on camera, for Werner Herzog.

Their new film Bucking Fastard premiered at the Venice Film Festival on Thursday, marking the first time the Mara sisters have shared the screen. Herzog wrote and directed the drama, which follows two sisters so close they speak in unison, love the same man, and share the same dreams (Variety).

At a Venice press conference, Herzog said he had wanted to make the film for years, but it was only clear the project could work once he met the Mara sisters in person. He scheduled a two-week rehearsal period for the unison speaking. He stopped it after five days. "Complete confidence," he said, according to Variety — they hardly needed the practice.

Kate Mara described the experience of speaking in unison as "almost like a song," saying it came with far more ease than either sister expected. Rooney Mara admitted the idea of playing the same kind of person was initially daunting, but found that a lifetime together had created an unspoken world between them that required little work to access (Variety).

The film is loosely inspired by the real story of Freda and Greta Chaplin, British identical twins who became tabloid sensations after both fell for the same neighbour — a man who eventually took out a restraining order against them. The title Bucking Fastard comes from a spoonerism — a swap of the first sounds of two words — that the Chaplin twins apparently uttered simultaneously while in court (Variety).

Orlando Bloom and Domhnall Gleeson round out the cast. Herzog, the influential German filmmaker behind Nosferatu the Vampyre and Aguirre, Wrath of God, is a Venice regular: Scream of Stone, The Wild Blue Yonder, Bad Lieutenant: Port of Call New Orleans, and My Son, My Son, What Have Ye Done? all premiered at past editions of the festival (Variety).

The path to Venice was not straightforward. Herzog turned down an invitation to screen the film at the Cannes Film Festival earlier in 2026, according to Variety. He had first approached the Mara sisters in 2024 with what Kate Mara called a "beautiful letter" asking them both to star (IndieWire). By May 2025, Kate Mara was already calling the project one of the greatest experiences of her life (Variety). A first clip featuring the sisters in eerie sync was released in July 2026, covered by The Film Stage and The Playlist.

Rooney Mara's credits include The Social Network, The Girl With the Dragon Tattoo, Her, and Carol. Kate Mara is known for House of Cards, 24, and American Horror Story: Murder House. Bucking Fastard is selected for the official competition of the 83rd Venice International Film Festival and also screens at the Toronto International Film Festival (La Biennale di Venezia; TIFF). Herzog is also set to be honoured at the San Sebastián Film Festival (Variety).

What makes the casting feel almost inevitable is the thing Herzog spotted: two siblings whose bond predates the script. The director spent years convinced the story was unfilmable. Then he met the Maras, and five days later, the rehearsals were over.