Agricultural festivals. Nature spirits. Fertility rites. Pagan cults. Human sacrifice. Are these elements of horror? Or something a bit more subtle and complex? There’s a narrative category for stories containing this kind of imagery and vibe: folk horror. And if you don’t know what folk horror is, let me take you by the hand, and lead you to the forest’s edge, or maybe to this field of corn, and show you…some things. Consider this a primer for the horror cinema fan who’s not familiar with the folk horror sub-genre.

After Ari Aster’s iconic debut film Hereditary, horror fans are thrilled and excited about his forthcoming feature Midsommar. Set in Sweden, it appears to contain some of the sort of pagan sacrificial cult elements that Hereditary featured, but in a different cultural context. And yet, Hereditary wasn’t about a pagan cult so much as it hinted at the existence of one. Those subtle hints and fragments made us curious and creeped out, and possibly haunted our dreams and maybe even our waking thoughts (as the most effective horror story should, with just enough information and compelling imagery to stay with us for an unnervingly long time).

And that is more or less how folk horror works: it’s the things that are not quite seen, that are not explicit, that are strangely familiar and yet unknowable, that grip us and terrify us, as if we’re not sure what’s lurking in the shadows, even if we can hear its breath and smell its sweat. Folk horror is sensual and earthy: even its ghosts are somehow corporeal, smelling faintly of ancestral secrets.

There are no hard and fast rules for qualifying what is and isn’t folk horror, but there are a few characteristics that seem to be common. One theme that is central is landscape, and its evocative power. Howard Ingham, author of We Don’t Go Back: A Watcher’s Guide to Folk Horror, puts it this way: “Out in the isolated places unusual superstitions flourish, and these are the places we came from. The old places. Even if the old gods have died, there’s something about these ancient geographies that makes new gods flourish where the old once reigned. The old grounds, lain fallow, are fertile for this sort of thing. But we don’t go back. That way leads to madness.”

Landscape is indeed a powerful presence in this definitive trio of folk horror films: The Witchfinder General (1968), The Blood on Satan’s Claw (1971), and The Wicker Man (1973). These three classic works, usually referred to as “the unholy trinity” of folk horror, have other elements in common.

They’re English (English folklore being the source for much of the occult revival literature and culture that found its way to the United States in the 1960s and 1970s). They portray a belief in animism or paganism, i.e. a divine force imminent in nature. They put forth ideas of human sacrifice or punishment as ways to appease ancient spirits of the land/location. There are usually a number of characters who share a belief system that other characters might find superstitious or supernatural; this sets up a dilemma of reliability. They portray landscape in an aesthetic way (visuals, sound) that feels strange, scary, evocative, “weird” or otherwise unsettling. They were created in the wake of the second occult revival, when peoples’ curiosity about ancient myths and lore was awakened.

Folk horror as a definitive sub-genre was first mentioned, apparently, by Mark Gatiss in a BBC 4 special from 2010 called “The History of Horror.” Gatiss noted that unholy trinity mentioned above “shared a common obsession with the British landscape, its folklore and superstitions.” Since then, kindled by a growing interest in this fascinating sub-genre, horror fans have been falling all over themselves trying to recommend their darlings as examples of folk horror. Arguments ensue at times, but the field of recommendations is a rich world to be explored.

The 1970s were, of course, a rich time for folk horror: in addition to the unholy trinity, there was The Dunwich Horror (1970), Valerie and Her Week of Wonders (1970), Walkabout (1971), Wake in Fright (1971), and Picnic at Hanging Rock (1975). Later came Eyes of Fire (1983), and The Company of Wolves (1984). The wonderful rural vampire tale, The Reflecting Skin (1990). The incomparably-influential, low budget fluke, The Blair Witch Project (1999), and the strange, original Wisconsin Death Trip (1999). Consider The Village (2004) and Pan’s Labyrinth (2006). Howard Ingham mentions some earlier films as being very influential as well: Jacques Tourneur’s Night of the Demon (1957), and going way back, Häxan (1922), an influence on The Blair Witch Project filmmakers, as was Cannibal Holocaust (1980), arguably the first “found footage” film.

And, post-2010, we’re now seeing filmmakers who seem to be crafting intentional examples of folk horror. Consider the brilliant Norwegian mockumentary Trollhunter (2010). Consider Kill List (2011), Sightseers (2012) and A Field in England (2013); thank you, Ben Wheatley! Consider Crow (2016), The Ritual (2018) and The Apostle (2018). There have been some television series that have a folk horror vibe also, going back to 1978 with the mini-series of The Dark Secret of Harvest Home, or 1984’s excellent Robin of Sherwood, and more recent examples like Detectorists (2014), Dark (2017), or Requiem (2018). And it’s worth mentioning that Stranger Things, the super popular show that debuted in 2016, replete with many 1980s horror film references, also bears some markers of folk horror.

While Hereditary’s folk horror elements may have been subtle, Midsommar looks to be a sort of folk horror sampler, with every chocolate in the box hiding a delectable, terrifying trope of folk horror. There’s hikers who take an ill-advised path through the woods (The Blair Witch Project, Crow). There’s innocent people being lured into witnessing a pagan ceremony (The Wicker Man, Kill List, The Ritual). There’s consumption of herbal intoxicants (A Field in England, Crow). There is ritualized performance with music (The Wicker Man, Crow, Robin of Sherwood, Kill List). There appears to be ceremonial human sacrifice (seen in most of these films). Aster seems to be attuned to a strong, growing vibe among intelligent horror fans, a hunger for the rich nuances of folk horror, and Midsommar promises a hearty feast.

Why this thrilling sub-genre should be so relevant now is anyone’s guess. Perhaps in looking to a frightening past we can better understand our terrifying present; perhaps we may learn something about ourselves that will carry us forward in uncertain times. Howard Ingham says of post-millennial folk horror: “It is more than nostalgia at work in the rejuvenation of our pagan apple orchards; is it equally the plugging of a definite loss of something of ineffable, intangible importance.”

A24 will release Midsommar on July 3.