If the modern horror genre has taught us anything, it's that there's only one thing creepier than ghosts: orphans.
Combine the two and you're cackling like a maniac, as Mexican scaremonger Guillermo del Toro well knows after tingling spines with The Devil's Backbone and had everyone running from The Orphanage with the screaming ab-dabs.
Del Toro continues his campaign of orphanophobic terror as exec producer of this superior ghost opera, directed and adapted from his own short by Andres Muschietti, alongside his co-writer-wife Barbara and Neil Cross, creator of TV's Luther and veteran of, appropriately enough, Spooks.
It all begins when the stock market crash in 2008 prompts a desperate banker (Game of Thrones villain Coster-Waldau) to kill two colleagues and his wife before absconding with his two young daughters.
Five years later, the killer's brother Luke (Coster-Waldau again) is about to give up the search when the girls are miraculously found living like animals in a cabin deep in the Virginia backwoods.
Under the supervision of eminent psychiatrist Dr Dreyfuss (Daniel Kash), little Lilly (the impressively spooky Isabelle Nélisse) and her sister Victoria (Megan Charpentier) are released into the care of Luke and his Goth musician girlfriend Annabel (Chastain, enjoying the change from the serious stuff with black bob and full sleeve tattoos).
Even with the palatial home and funding provided by Dreyfuss, how a penniless illustrator and a child-resistant rock chick end up with guardianship over two psychologically unpredictable under-nines is a mystery. But it's nothing compared to the mystery of how the girls survived.
All Victoria can tell them is that they have been cared for by an entity called “Mama”. And, as becomes freakily and frighteningly clear, Mama is not about to let their custody go uncontested.
Eliciting regular bursts of goosebumps and making sly nods to The Shining and The Exorcist, it's clear that the Muschiettis and Cross have done their homework.