It’s no “Rosemary’s Baby” — or even “It’s Alive” — but the Danish supernatural thriller “Shelley” is a fair addition to the “natal horror” genre. Writer-director Ali Abbasi’s debut feature takes too long to intensify, but down the stretch it’s as disturbing as the scariest chapters of “What to Expect When You’re Expecting.”
Ellen Dorrit Petersen stars as Louise, a frail woman who lives off the grid with her husband Kasper (Peter Christoffersen) and her Romanian maid/nurse Elena (Cosmina Stratan). Louise and Elena’s relationship evolves from employee/employer to something friendlier, once the immigrant agrees to be a surrogate mother for her childless bosses.
That’s where the trouble begins. Disturbed by the family’s over-reliance on a creepy spiritualist — and physically tormented by unnaturally rapid changes in her pregnant body — Elena goes mad. Then the baby arrives, and the situation gets worse.
Abbasi never fully explains what’s happening; and because Louise and Kasper live in a home without electricity, sometimes it’s literally impossible to see. After a strong start, “Shelley” becomes frustratingly vague in the middle, before rebounding with a finale that makes the implicit menace more explicit.
Like a lot of its “pregnancy is terrifying” predecessors though, “Shelley” is best when it feeds off new parents’ fear of the unknown. Add to that a layer of social critique — about how the privileged exploit their servants — and the movie offers a strong take on how evil can enter the world with alarmingly little gestation.
Running time: 1 hour, 32 minutes.
Playing: Arena Cinema, Hollywood