WARNING! MASSIVE SPOILERS AHEAD

HBO’s True Detective is a dark and desolate story of obsessiveness disguised as a police procedural, and it’s unabashedly deep. It’s also that rare show that’s heavy in a good way—undeniably riveting, unsettlingly satisfying, intellectually girthy and pants-poopingly intense. Created and written entirely by Nic Pizzolatto, the plot revolves around two detectives on the trail of a ritualistic serial killer who leaves juicy occult breadcrumbs wherever he goes, like a satanic Hansel. Broody Rustin Cohle (Matthew McConaughey) and his partner Martin Hart (Woody Harrelson), unpack the details of their original case, a 1995 murder of a prostitute named Dora Lange, for a pair of young detectives in 2012. But the case itself is evolving in real time, and the narrative is crafted from multiple vantage points, moving backwards and forwards through decades. In this week’s penultimate episode, the action has finally caught up to itself in the present day, setting up a finale on Sunday that will hopefully answer a lot of big questions.

What really brings depth to True Detective’s unfolding mystery is the undercurrent of pagan symbolism and mythology, which the average HBO subscriber might not realize is actually rooted in a niche 19th century literary genre called “weird fiction,” most commonly associated with the authors Ambrose Bierce, HP Lovecraft, Thomas Ligotti, Shirley Jackson and Robert W. Chambers. Nic Pizzolatto has professed to be an avid fan. Formed at a time before science fiction and fantasy went their separate ways, weird fiction combines elements of both along with the supernatural, horror and the occult. Thematically, weird fiction takes a particular interest in humanity’s descent towards madness, sometimes viewed as an inevitability always lurking in the distance, as in Robert. W. Chamber’s The King in Yellow and HP Lovecraft’s At the Mountains of Madness.

To understand the “weird” references Pizzolatto has interwoven throughout True Detective—and ultimately the sadistic killer (or killers) we’ve been following all season—you have to start with Ambrose Bierce, who wrote a short story in 1886 called An Inhabitant of Carcosa. (io9’s Michael M. Hughes did a nice job of first cracking the code). The Bierce story concerns a man from the city of Carcosa who wakes up from a deep sleep and tries to figure out where he is. He wanders aimlessly until he comes upon his own grave and realizes that he is dead and that the wasteland he has been wandering through is all that’s left of Carcosa. The story was a cult favorite and influenced many writers, most importantly Robert W. Chambers, whose 1895 book of stories, The King in Yellow, figures heavily in True Detective. Several stories in the book revolve around a fictional play, also called The King in Yellow, which drives its viewers completely mad. One of the few written sections of the play in the book repeatedly name checks Carcosa. The King in Yellow is steeped in the occult, from a supernatural being of the same name, to secret powerful documents and sinister churchmen. Chambers, in turn, influenced countless other writers in the genre, perhaps most notably HP Lovecraft, the most well-known weird fiction author, who focused on cults, madness and ancient cosmic entities.

So now that you know the basics, here’s an episode-by-episode guide to decoding True Detective.

The Antlers

Early in the premiere, Cohle and Hart come across the body of Dora Lange, placed in a ritualistic kneeling position with some unusual headwear. True Detective isn’t the only moody, visually stunning, hour-long drama currently featuring antlers: NBC’s Hannibal displays them prominently in its serial killer imagery. Nor was Hannibal the first; in the 1979 miniseries of Stephen King’s Salem’s Lot, James Mason impaled someone on the pointy objects, and Kiefer Sutherland was killed by a pair in the ‘80s vampire flick Lost Boys as well. The antlers are part of a crown, the first reference to the idea of a king or royalty, which will later be revealed as the Yellow King.

The Spiral Tattoo

The second reference to The King in Yellow appears almost simultaneously on murder victim Dora Lange’s back. The spiral tattoo is graphically similar to an Irish megalithic symbol found inside Newgrange, a large prehistoric monument with a stone passageway and chambers within. The tattoo, however, is more symbolically reminiscent of the “yellow sign” which factors into Chambers’ stories. The yellow sign is not particularly well-defined in Chambers’ work, and physical descriptions only come by authors borrowing the symbol later on.

However, the first story in The King of Yellow, “The Repairer of Reputations,” implies that anyone who possesses a copy of the sign is under the sway of The King of Yellow, like something out of The Manchurian Candidate or under Professor X’s telepathic control in X-Men. Amongst the little information given about the yellow sign is the suggestion that it’s from an alien dimension where Carcosa existed.

The Creepy Stick Teepees

The stick latticework structures, called bird traps or devil nets by a reverend Cohle and Hart interview, recall a more modern weird fiction-influenced short story titled Sticks by Karl Wagner, who was inspired by the stick lattice drawings of horror artist Lee Brown Coye. In the Wagner story, the stick lattices are used by an underground cult that attempts to bring about the rise of ancient beings. Sticks is considered part of the Cthulhu Mythos genre, a subset of weird fiction that takes place within a particular HP Lovecraft universe that revolves around the existence of uber-powerful aliens who ruled earth millions of years ago but have since fallen into a near-death sleep. Got it? Sticks has been cited by Pizzolatto directly as an influence.

The Green-Eared Spaghetti Monster

Hart and Cohle come across the report of a third young girl who claimed to have been chased through the forest by what is described as a “green eared spaghetti monster.” The monster is reminiscent of HP Lovecraft’s Cthulhu, an ancient cosmic powerful underwater creature who, in appearances like The Call of Cthulhu, is hibernating and waiting to be called out of his near-permanent slumber by a cult of fanatics. The monster also bears a certain resemblance to a pagan figure known as the “Green Man” who was carved on churches throughout medieval Europe. The figure is suspected to be associated with fertility or nature in earlier carvings, the earliest of which appeared in 400 AD, etched into the French tomb of St. Hilaire-le-Grand.

“Someone’s Memory of a Town”

“This place is like someone’s memory of a town, and the memory is fading,” Rust remarks, when leaving the coroner’s office where Dora Lange’s body was examined. The comment is a reference to An Inhabitant of Carcosa, in which Bierce describes a protagonist who wakes up only to realize he is dead and walking through the ruins of the ancient Carcosa, a once great metropolis, that’s now merely a fading memory.

The Black Star Tattoo

Detectives Cohle and Hart find out about murdered Dora’s friend Carla from Dora’s ex-husband. When they interview her, they see she has a noticeable neck tattoo of black stars. Black stars feature prominently in Chamber’s fictional play “The King of Yellow.” The lyrics to “Cassilda’s Song” from the play, which opens Chambers’ book, read “Strange is the night where black stars rise,” and black stars are continually described as hanging over Carcosa.

The Diary

Dora Lange’s diary, which the detectives find in a “hillbilly bunny ranch” is filled with allusions to the Yellow King and black stars. It’s also the first directly spelled out reference to Carcosa, Bierce’s mystical ancient city.

Spiral Tattoo: Bird Edition

Cohle, we’ve learned earlier, has hallucinations dating from his days as an undercover narc, placing him one step closer to insanity than most men. He claims he can tell the difference between reality and fantasy—but as a viewer, it’s far less clear. Here, Cohle hallucinates Dora Lange’s spiral tattoo, manifested in a flock of birds that represents the yellow sign. Cohle’s inability to decipher real from unreal is reminiscent of many Lovecraft characters, including the protagonist from “The Shadow Out of Time.”

The Cave Painting

Cohle and Hart discover a poster for the “Friends of Christ Revival” church in Dora Lange’s diary, but when they find it, it’s been burned down. Hiding on a remaining wall, however, is a primitive painting resembling Dora Lange as she was found, worshipful and naked, with her antler crown.

“In the Name of the Lord”

Joel Theriot is a preacher for a tent revival church that Dora Lange joined toward the end of her life. His surname is one letter away from that of Master Therion, an alias of prominent early 20th century occultist Aleister Crowley, associated with 666, the number of the beast. Theriot also notably makes the sign of the cross backwards, right to left, instead of left to right, perhaps indicating a deviation from his stated religious ideals.

The Gas Mask

Episode three ends with a menacing shot of Reggie LeDoux, the tall man described at the church revival, wearing an old gas mask with a hose that swings back and forth as he walks through the woods in nothing but a jock strap. The gas masked figure may be another reference to Lovecraft’s ancient Cthulhu, whose face, full of octopus-like feelers, is eerily similar to the inhuman-looking LeDoux. It’s also reminiscent of a line from Dora’s diary: “I closed my eyes and I saw the king in yellow moving through the forest.”

Stones in the Woods

A return visit to Charlie Lange further illuminates the life of Reggie LeDoux. LeDoux, who apparently also has a spiral tattoo, is into devil worship, and Lange prominently mentions both Carcosa and the Yellow King while referring to rituals that take place near stones out in the woods. Stones play an important role as a setting of occult rites in weird fiction. Lovecraft’s The Durwich Horror, for example, describes a circle of stones as the location for the calling out of an ancient cosmic entity.

“I Met a Man on the Way to Carcosa”

As he’s being handcuffed, LeDoux ominously warns that “black stars rise” and that Cohle will be “going to Carcosa now.” He also mentions “twin suns,” another bit of imagery from Chambers’ “Cassilda’s Song” in The King in Yellow, which reads “The twin suns sink behind the lake.” His allusion to Cohle being on his way to Carcosa may be euphemistic for a road to madness.

The Crown in the Tree

In a flashback to an unspecified time, we see Hart’s two innocent-looking daughters fighting over a crown, which eventually gets thrown up in the air and lost in a tree. The crown is reminiscent of the crowns we’ve seen on Dora Lange, and its appearance in the tree places it in a similar position to other crowns over the course of the season. It’s an ominous portent for the girls; wearers of the crown have only turned out dead so far.

The Black Hole Wreath

After hearing that the Yellow King is still out there, Cohle decides to start investigating again. In the spot where Dora Lang’s body was found is now a wreath, seven years later, under a devil net. The wreath has a multitude of potential meanings. Appearing seven years after the original murder, it represents the flat circle of time LeDoux crowed about; all this time later and yet nothing has changed. The center of the wreath is a portal, a dark chasm to another world, like the Stargate from the early ‘90s film of the same name. It could also lead to the underworld. The large tree under which the portal and devil net are found resembles a World Tree, which is prominent in several old religions, including Norse mythology. The tree supports the heavens atop its branches and connects to the underworld through its roots. In this one location, heaven, earth and the netherworld are all connected. The dark chasm could also lead to Carcosa. “In far cold Carcosa…lies madness,” wrote Joseph Polliver in an anthology of tales revolving around The King in Yellow. Just like LeDoux warned.

The Elementary School

When Cohle backtracks to the abandoned parish school from a few episodes earlier, he finds symbols we’ve seen before, a whole collection of stick lattices, black stars painted on windows and some new creepy white paintings of what appear to be angels with little halos. Earlier in Dora’s diary, we saw the line, “The kings children were marked, and they became his angels.”

Catching Light in the Devil Net

As Cohle stands in the abandoned school holding up one of the many devil nets he found there, a beam of light shines at a 45 degree angle through the only window. The rays of light are visible through the dust of the dirty building, and appear to be captured in the net, which just might be doing its job corralling Satan’s essence. The scene recalls a baroque painting with a single source of light illuminating everything through a window. “You got a demon, little man,” Dewall tells Cohle earlier in the fifth episode. “There’s a shadow in you, son.” The single light intermingles with the shadows, heading straight for the net while Cohle remains primarily bathed in darkness.

The Storage Locker

In episode seven, Cohle has marked up his storage unit with notes about the potential killer still on the loose. He has more details about Marie Fontenot, the girl who was presumed escaped with her father before the 1995 Dora Lange murder. “Scars,” “Yellow King,” and “Carcosa” are the largest markings on the wall.

The Crown Photos

Rust Cohle believes he has found a photograph of Marie Fontenot with the antler crown on her head. Her aggressor wears a mask. Marie’s antlers are similar to the patterns found on Dora Lange, and the crown is consistent with the Yellow King philosophy we hear from Reggie LeDoux; Fontenot and Lange are both sacrifices to the king.

The Painting

This picture of Hart’s daughter Audrey posing with her painting contains signs we’re familiar with. The face contains black stars and the woman has a yellow hat. Both are reminiscent of the yellow king, which raises a question we never thought to ask—was Audrey molested by or somehow associated with the Yellow King?

The Files

When Cohle and Hart interrogate an employee of Reverend Billy Lee Tuttle’s father, Sam, she mentions that the person with scars was Sam’s grandchild (though she’s suffering from some possible dementia). They show her a journal with devil nets and she asks if they know Carcosa, Chambers’ terrifying dreamland. She descends into indecipherable babble before her daughter gets wind of the situation and ushers them out. “Death is not the end. Rejoice,” she tells the detective before they leave.

The Scars

The lawnmower man Cohle and Hart bumped into before settling on Reggie LeDoux shows his facial scars at the end of episode seven, suggesting he’s the green-eared monster we’ve been after. The first time we met him, he had a beard. While the scars hardly give him the Lovecraftian Cthulhu air we were expecting, he just might be as monstrous on the inside. He’s a modern Cthuluhu, hidden at first, but visible to those who know what to look for.

The Masks

Animal masks like the ones in the grainy black-and-white video Cohle stole from Tuttle’s safe are traditionally worn in rural Cajun Mardi Gras celebrations. These traditions themselves draw from ancient masked begging processions known as “luck visits,” which were once widespread in Europe. While the tradition faded around the mid’20th century, the last two decades have seen a revival. Next week, if Nic Pizzolatto isn’t outrageously cruel, we’ll find out just who’s wearing them.