The strain of new naive cinema can be so stuffed with quirks, so determinedly guileless that it starts fraying the nerves as well as the seams. But Rebecca Thomas's gauzy debut about a 15-year-old Mormon who believes she's had an immaculate conception after hearing a cover of Blondie's Hanging on the Telephone is so deftly done it's three parts enchantment to one part irritation. Its big draw is Julia Garner – a support in Martha Marcy May Marlene, magnetic in the lead. But the other performances – Aitken as the brother accused of rape, Culkin the rocker she meets in Vegas, even Zane as her sly pastor father – are more finely spun than you'd expect; likewise the portrayal of the community (Thomas grew up Mormon). A genuine nativity, then, rather than just being knowingly naive.