Rating: Patricia Highsmith's writing is something that's deceptively difficult to transfer to the screen. Her characters are by description immoral husks purely out for themselves, but there's an overlooked complexity that lies hidden in her prose; the protagonists aren't the bad guys, but regular people with slightly-skewed ethics that over time lead them down an irreversible path. Most films tackling her novels tend to miss that, turning tricky stories into simple antihero parables. Carol, based on her second novel, The Price Of Salt, doesn't have the murderous pivot of The Talented Mr Ripley or Strangers On A Train, but it still has an underlying subtlety to its character's motivations that would have been easy to overlook (sexual ambiguity is a theme of Ripley that cinema consistently simplifies). Thusly Todd Haynes cannot get enough praise for his handling of this lesbian romance set in fifties America. Typical social pariahdom isn't rotely trotted out and the mise-en-scène goes beyond just invoking the times, the setting tailored to subtly accentuate the story - we haven't seen period New York so uniquely yet intoxicatingly realised since Jury Presidents' the Coen brother's Inside Llewyn Davis. Music here is the key, with era-accurate pieces topping off some impeccable, but in the film understated, set design. Haynes clues you into what filmmaking tricks to watch out for from early on. A wannabe film critic rewatches a film for the sixth time to log the differences between what the characters say and what they feel (a practice Carol is begging for), while an obsession with photography opens up attention to some evocative cinematography. Interiors have walls that fill the frame, cutting off glimpses of the characters and allowing them to enter shot from what should be logically impossible angles. All of that, though, is window dressing for the story itself. As nuanced yet instantly captivating as Haynes' direction is, what turns Carol into a masterwork is the director's understanding of the personalities and arcs of his characters, and the subsequent decision to drop much of it in as sly asides. Cate Blanchett (the titular middle-aged, middle-class, privately open bisexual) and Rooney Mara (a department store worker captivated by the older woman) are wholly believable as emergent lovers with a mostly unspoken bond that aches in its early equivocation. Carol is the more typical Highsmith creation; her true motives feel oddly distant and from the off there's the potential for something really dark hidden behind the measured exterior. She first enters the film as a purposed figure, bordering on femme fatale, but this front hides an incredible fallibility; she's at constant loggerheads with her separated husband, played by a great Kyle Chandler - wronged by a previous homosexual affair, despite filling an antagonist role, he has perfectly understandable motivations. In the face of this, as well as the discovery of young love, Blanchett alternates between floating grace and unmeasured upset, a woman who socially exudes power but secretly has none. Repression isn't carried over to Mara's Terese. She may be the one discovering her feelings (interestingly, the word "lesbian" is never once used), but there's no dominating internal conflict to begin with, and when it does come the web is so tangled it's about much more than coming out. She states that she finds herself perpetually subservient to others, and through her picking of partners with a sexual past she's certainly on the backfoot, yet it is her who first strokes Carol's hand in public without batting an eyelid and finally instigates the pair sleeping together. That sex scene, destined to be a dominant talking point (it's going to take over from sister Kate's scenes with Kevin Spacey in House Of Cards as a key discussion around the Mara Christmas table), isn't just a moment of touching embrace. It's the culmination of the character's journeys and marks a key narrative turning point in the film; after the short and unfussed clarity, the ramifications of what the pair is engaging in come firing home. Framed by a late meeting between the pair and told predominantly in flashback, Carol never trudges through the slow development with a sense of obligation. It's a perfectly paced film, with the two women driving the audience through their story at the pace they require, and stands as the best In Competition offering from Cannes so far. Last year's The Two Faces Of January was the first time since 1960's Purple Noon that a filmmaker got Highsmith's characters, but now we have something more; a genuinely wonderful film that, despite its atypical source, finally gives her writing its deserved work. Keep up with all of our Cannes 2015 coverage on the official page here.