Like many genre exercises before it, Open Grave is all premise and little payoff. Its opening hook is undeniable: A man wakes up in a mass grave, alone among dozens of corpses, without any memory of who he is or how he got there. Writers Chris and Eddie Borey have assembled an appealing template for narrative cartwheels, and as diverting entertainment, this horror-mystery hybrid mostly delivers, but flimsy plotting, opaquely drawn characters, and a crudely predictable visual design strip Open Grave of any real nuance or depth. As our John Doe gathers more information and makes more disturbing discoveries, the film feels more and more directionless and slight.
After an effectively moody opening, Open Grave encounters trouble with the arrival of the other principal characters, five strangers who are hiding out in an abandoned mansion near the grave. The unit's collective lack of memory leads them to comb the house and its woodland surroundings for any hint about their identities, but the real tension in these sequences is internal. The grave-fleeing protagonist (Sharlto Copley), whose name is eventually revealed to be Jonah, is immediately marked as an outlier (the others all woke up inside the house, with photographic proof that they once knew each other), and the film's most successful moments focus on the question of his possible culpability. Jonah constantly struggles to determine whether he's the hero or villain of this nightmare, and as played by the always-compelling Copley, his crisis makes for a tense and engaging journey.
What's going on outside Jonah's head isn't always as gripping, as the other characters are weirdly devoid of personality along with memory (their occasional outbursts of panic or rage feel arbitrary, even boring). The exception is a mute woman (Josie Ho) who seems more knowledgeable than the others, but can only communicate via written Chinese. Gripped by crises of responsibility and communication, she's the only character other than Jonah who feels real. As these compellingly ambiguous characters suggest, Open Grave works best when it's difficult to read: In its most disorienting sequences, it teases out just enough information to suggest an array of horror tropes, resembling a Jonestown parable one moment, then an insane asylum thriller, then a zombie apocalypse.
But these teases also reveal an uncertainty among the writers and director Gonzalo López-Gallego about the real film they want to make, an uncertainty amplified by the use of half-baked flashbacks—shot in eye roll-worthy sepia tone—and plenty of narrative dead ends. The former in particular is so obvious a narrative device (it quickly becomes the only means of delivering information and furthering plot) that it undoes whatever tension is accumulated by the strong opening scenes. Open Grave establishes a logic of memories slowly and randomly re-percolating over time, which makes for dreary suspense; anticipation becomes a moot point, and events don't build organically out of each other so much as they appear and disappear like flashing lights. Individual moments linger, like a wonderful sequence in an abandoned hospital, presented with little fanfare, that imperceptibly shifts from subtle to terrifying to comical in a matter of seconds, but as a cohesive object, Open Grave is merely a rough draft of a thriller.