Some premises sell themselves. An all-woman heavy metal band gets stranded in a town packed with cannibals, vampires, a warlock and a werewolf. I didn’t need a synopsis. I needed snacks.

That’s what makes Devour so frustrating. Director Scott B. Hansen and screenwriter Desirée Hansen hand themselves a gloriously ridiculous B-movie setup. KateLynn E. Newberry leads the cast alongside...