LONDON: Learning that “Nanny” is the first horror film to win the Grand Jury Prize at Sundance earlier this year might lead some to assume they’re in for something of a screamfest — but this is a far more subtle movie than that. Helmed by Nikyatu Jusu, “Nanny” is a quietly disconcerting thriller on Amazon Prime Video, full of slow-build tension and sinister insinuation — this is no blood-and-guts bonanza. For the latest updates, follow us on Instagram @arabnews.lifestyle Aisha (Anna Diop, recently seen in “Us” and DC’s “Titans” show) is a Senegalese nanny for a wealthy New York couple. Though she gets on well with their daughter Rose, Aisha is at the mercy of her employers’ lackadaisical attitude to their undocumented employee — they pay her salary late (or not at all), give scant attention to their child’s needs, and tread all over the very fine line between making Aisha feel welcome and simply taking advantage. Rose’s mother Amy (Michelle Monaghan) is flaky and jealous. Her husband Adam (Morgan Spector) is creepy and evasive, and both seem surprised that Aisha might not be at their constant beck and call. But while this social commentary is scary enough — and Jusu wields the precarious nature of Aisha’s situation with aplomb — there’s something more sinister at play too. Aisha is haunted by visions of drowning, of serpents and spiders. It’s often unclear precisely what these hallucinations mean, as Jusu instead ratchets up the surreal tension without resorting to cliched theatrics. But, aided by Diop’s composed performance, “Nanny” paints a world in which some of the scares are imagined, and some are simply the pitfalls of modern society for an entire generation of undocumented workers in big cities. As Aisha tries desperately to scrape together enough cash to fly her son out to join her — Amy and Adam are stunned when forced to accept that her life might be about more than simply being absorbed into their family — Jusu’s film creeps towards a crescendo that, in truth, it struggles to completely pull off. And while the ending of “Nanny” feels a little flat and lackluster, it remains that most wonderful of entities — a combination of director, cast and story all working in wonderful, slightly unsettling harmony.