Let’s get one thing out of the way first: I did not entirely understand everything that happens in “Cuckoo," a new indie horror in theaters Friday. This could be more of a me problem than with the storytelling, but there are a lot of strange things happening at this particular Alpine resort. It's run by a bespectacled German hotelier named Herr König, played with an off-kilter menace by Dan Stevens. Some of the occurrences are underexplained, others underexplored. Herr König seems particularly worried about things that happen after dark, but not so much about guests wandering into the reception and general store in a wobbly stupor and vomit. Are they drunk? Sick? Should someone help them? All we get is: “It happens.” The hospital, too, is eerily empty. Sonic vibrations often ripple through the land, causing scenes to repeat until reaching a violent crescendo. And no one seems to listen to or care about anything 17-year-old Gretchen (Hunter Schafer) has to say, no matter how banged up she gets. The quick escalation of her injuries, and the widening disinterest of her father, approaches comedy. Ambiguity can be wonderful for mystery and worldbuilding; It can also be frustrating. And more often than not, detailed explanations just make everything lamer. “ Cuckoo ” dips into all of the above. Even so, it is undeniably fascinating, original and even occasionally fun, in a very twisted and deranged way in which laughter is your involuntary response to something horrifying. In her captivating lead performance, Schafer really goes through it, both physically and emotionally. It also features Stevens sporting tiny, rimless glasses with sinisterly scandi-cool monochrome outfits, and a screaming ghoul with Hitchcockian glamour in a hooded trench and white-framed oval sunnies. Rarely is it a bad idea for a horror film to lean into style, and “Cuckoo” fully commits.