Two of America’s most talented film stars, Rooney Mara and her older sister Kate Mara, find the ideal role in Bucking Fastard. The singular use of ‘role’ here is apt, for in this unique drama, the Mara Sisters play Jean and Joan Holbrooke, two Irish siblings who act as one. Though not twins, they dress the same, act the same, live together and speak in unison. It’s an eerie personality trait, one that sets these girls adrift in the modern world.

The fairytale-esque Bucking Fastard is the latest work from German maestro Werner Herzog. The director of such acclaimed films as Aguirre, Wrath of God and The Enigma of Kasper Hauser has spent much of the last decade working in documentaries, but here he crafts an original story, albeit one loosely inspired by his own encounters with Greta and Frida Chaplin, identical twins he met in England in the 1980s. The Chaplins became briefly notorious when they got involved with the same man, who later had to file a restraining order against them.

Similarly, Bucking Fastard begins as Jean and Joan meet, and share a bed with, a Dublin limousine driver, Gareth Mulroney (Orlando Bloom). Their passion for this slightly oily man, who calls them his "cowgirls", spills over into something stronger and stranger. "We loved him. He was the joy of our lives," they chorus, but before long, Bloom’s promiscuous fellow is onto the next woman in his life, leaving them bereft. "Is it a crime to love?" they ask. Perhaps not, but their increasingly erratic behaviour soon sees them in court (where the titular malapropism is spoken, much to everyone’s amusement).

It’s about here where Herzog departs anything resembling the Chaplins' story, as the tale moves on six months and Jean (Rooney Mara) and Joan (Kate Mara) continue their quest to find love. It’s a journey that sees them both encounter the kindness of strangers – including Domhnall Gleeson’s Timothy – and the suspicion of some townsfolk. Theirs is a search not just for love, but for a world free from the strict social codes they clearly can’t adhere to. "There must be a place for us somewhere," they murmur.

Comparable to Herzog’s own seminal movie Fitzcarraldo, in which Klaus Kinski’s character dreams of building an opera house in Peru, Bucking Fastard feels like the Herzog of old. Unerringly romantic and utterly bizarre, it’s also darkly funny, with a story that seemingly borrows from the fables of Celtic folklore. Animals, notably foxes, also feature strongly, especially when the girls leave Dublin behind and head out into rural Ireland in search of a new beginning.

Rightly, much of the attention deserves to fall on the Mara Sisters, who have never acted together before. Thankfully, they saved their first on-screen collaboration for something as singular as this. Speaking their lines in perfect harmony (and even hoovering together in one scene), it’s a highly unique performance, one that Herzog moulds into something utterly strange and compelling. Credit also goes to Bloom for his work as the slippery love interest, a character far removed from the dashing roles of his youth.

Shot by Herzog’s long-time collaborator Peter Zeitlinger, and scored by another of the director’s regulars, Ernst Reijseger, the film truly benefits from the lush Irish backdrop, especially for scenes later in the film at the famed caves of Kesh. Arguably Herzog’s most off-kilter film since 2009's Bad Lieutenant, this poetic work may not suit all those looking for a straightforward love story. But it will charm the hopeless romantics out there, especially anyone who has ever strained to find love in their lives.

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