As much as Andres Muschietti follows all the rules in adapting his short film into a feature-length one, I give him credit for his conviction, and the polished, considered approach he takes to directing this stock horror film. Such careful consideration, however, drains Mama of the potential to surprise or to truly shock, and since he is disappointingly reliant upon jump scares to maintain our interest, this is a misjudgement, one that slows the film down. He plays on ideas hardly original to the genre, but with the occasional air of creepy portentousness that hits just the right note - equal parts intriguing and spine-chilling. These are abandoned as time passes, and the story lumbers around in circles, with an over-familiar backstory, loose ends as big as your leg, and the obligatory noisy nighttime-set finale, replete with CGI and a villain who has become far too humanised to be frightening any more. Like many filmmakers, Muschietti understands that suggestion is scarier than showing, but ends up showing anyway. His use of the more blatant horror tropes, the dream sequences, the shadowy monster, is generally pretty successful, yet consistently undermined by the familiarity of the material, and the leaden pace with which it gets nowhere. Jessica Chastain is convincing as a rock chick reluctantly accepting guardianship of two feral young girls whose history is far more interesting than the melodramatic story told for the majority of this dull film. It's inventive and unhinged, and quite unsettling. Everything Mama is otherwise not.