Our hero Ethan is contending with a strange kind of cyclical amnesia that makes dealing with the flesh-eating undead a good deal harder

As this highly derivative but mildly absorbing Canadian horror thriller kicks off, we meet Ethan (Douglas Smith), a young man seemingly on the verge of killing himself. He looks out over a picturesque stretch of Saskatchewan landscape bathed in magic-hour glow before we cut to a welter of confusing, often blood-soaked flashbacks (or flashforwards) – and his voiceover then explains that although his memory doesn’t work so well, he’d rather not remember most of his life anyway. That’s because unfortunate Ethan is suffering from a kind of cyclical amnesia, not unlike the disorder that bedevilled Guy Pearce’s character in Memento, which compels him to keep reintroducing himself to people he’s met many times before. This is a particularly dangerous condition to have because Ethan is living in the middle of a zombie apocalypse that’s turned everyone who hasn’t gone full zombie into skittish, trigger-happy survivalists desperately clinging to what little resources they have.

That even goes for Mae (Carrie-Anne Moss, who just so happened to have also been the co-star in Memento), a tough loner living in a secluded farm who seems to have taken Ethan under her wing. Or does she have a more nefarious plan in mind? Moss has one of cinema’s great poker faces, an impenetrability enhanced by those spectacularly sculpted cheekbones, so she’s well cast here as an enigma wrapped in a tattered parka. Ethan keeps telling Mae that he needs to find his girlfriend Emma (Kimberley-Sue Murray) who went missing after they were in a car accident; flashbacks fill in the young couple’s happy life before a virus turned people into human-flesh-eating shadows of their former selves. (These are slow zombies at least, a change from the recent fad for fast-moving brain-munchers like the ones in the 28 Days Later and Last of Us franchises, otherwise heavily referenced here.)