If you're watching True Detective: Night Country, chances are you've been glued to the screen scanning for clues like we are. And that means you're onto the spirals.

In the fourth season of the HBO series, this time helmed by showrunner Issa López, police chief Liz Danvers (Jodie Foster) and state trooper Evangeline Navarro (Kali Reis) can't stop finding these symbols in their investigation.

It's not the first time we've seen sinister spirals in this show. As Mashable's Kristy Puchko points out, "In Season 1 of True Detective, spirals were a creepy recurring symbol tied to the Yellow King and his mystical murder spree."

But what do the spirals mean? It's one of the burning questions we have for the season (along with those polar bears and what the hell that ungodly corpsicle is). Let's track them down in an act that will make a true armchair detective of us all.

Episode 1

Danvers makes the first spiral in the season herself as she's processing evidence related to the disappearance of the scientists from the remote Tsalal Arctic Research Station and the murder of Iñupiaq activist Annie Masu Kowtok (Nivi Pedersen). She inadvertently makes a spiral pattern of her printouts, finding her way to the pink parka jacket that will connect the cases before the actualspiral symbol starts showing up. Danvers and Navarro make a similar spiral processing evidence in episode 3.

Episode 2

After the discovery of the corpiscle, Danvers sweeps snow off the forehead of one of the frozen scientists and uncovers a spiral on the corpse's skin. Later, when Rose Aguineau (Fiona Shaw) is talking with Navarro, she asks whether the trooper saw the shape. When Navarro says she vaguely remembers seeing it before, Rose draws the shape in the snow and explains, "It’s old, missy. Older than Ennis. It's older than the ice, probably."

Navarro remembers Annie had a tattoo of a spiral. She shows Danvers a picture of the design, proving the connection between their cases. Danvers begrudgingly follows the lead and asks a former worker from the Tsalal facility, Beatrice (L'xeis Diane Benson), about the symbol, who supposes it to be linked to witchcraft or a "devil sign." Her colleague Blair (Kathryn Wilder) says she doesn't recognise it either.

Later in the episode, Danvers figures out that one of the Tsalal scientists, Raymond Clark (Owen McDonnell), had gotten a spiral tattoo on his chest four days after Annie's body was found. The tattoo artist tells Danvers that Clark cried for "sentimental" reasons when he had it done, and shares the photo Clark gave as a design reference; it's a photo of the tattoo on Annie's back, and one that indicates Clark and Annie were lovers.

Now officially teamed up on the cases, Danvers and Navarro find their way to Clark's creepy trailer, where a giant spiral (among other things) has been scrawled on the ceiling — above a woven, life-sized doll lying on the bed. By the end of the episode, they've figured out Clark's actually alive.

Episode 3

When Navarro is asking hairdresser Susan (Bridie Trainor) about Annie, she mentions Annie had showed Clark her tattoo when they first met, and that he was "fixated on it." Susan explains Annie came up with the design after seeing the spiral in recurring dreams in high school. "She got the tattoo, the dreams stopped," she says.

In the very last moments of the episode, when officer Peter Prior (Finn Bennett) hacks into Annie's phone, he shows Navarro and Danvers a video from it, a recording of her last moments alive in the ice caves we've only seen in the opening credits. After a terrible scream, Annie seems to drop her phone, which continues to film the cave ceiling — where a spiral skeleton of some form of prehistoric sea creature can be seen embedded in the ice. Coincidence?

Episode 4

When consulted by Danvers and Navarro, teacher Adam Bryce (Donnie Keshawarz) identifies the spiral skeleton as that of a prehistoric whale, preserved in ice caves near Ennis.

When Navarro and Prior investigate Oliver Tagaq's (Lance Karmer) place in the nomad camp on Christmas Eve, they find a drawing of the spiral on cardboard on the floor and a stone carved with the symbol, a petroglyph, sitting in the drawing's centre. Navarro takes the stone and asks the residents if they know what it means — they refuse to answer and stand in unison, defensively. Later, she leaves the stone accidentally at Eddie Qavvik's (Joel D. Montgrand).

In the dilapidated dredge, Navarro and Danvers find a giant spiral drawn on the walls before they find missing Tsalal engineer Otis Heiss (who survived the same type of injuries as the scientists but earlier).

Episode 5

When Navarro's doing laundry, Qavvik brings her the spiral stone she left behind, along with his friend who tells her, "My grandpa, he told me to walk away when I saw those. People would leave them as a warning for hunters," he says. "Places where the ice would swallow them whole." He's referring to the underground ice caves they've been searching for, referred to as the Night Country.

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Episode 6

After finding the caves and chasing their prime suspect, Clark, through them, Navarro and Danvers discover the underground lab where the Tsalal scientists murdered Annie. On the ceiling, they find the whale skeleton, marking the site. Later, when Navarro and Danvers are taking a break in the Tsalal Arctic Research Facility, Navarro reflects on her mother and sister's tendency to peel oranges in a spiral. Danvers later does exactly this and arranges the peel on her plate in the symbol we've seen.

Even later, when the pair finally figure out what happened to the scientists from questioning former Tsalal worker Beatrice (L'xeis Diane Benson), there's a spiral in her story. When the Iñupiaq women of Ennis herded the scientists into a truck, drove them out to the ice, and forced them to take off their clothes, Beatrice drew a spiral on Annie's initial attacker Anders Lund's (Þorsteinn Bachmann) head, instantly connecting the soon-to-be-frozen scientists with the murder — linking Danvers and Navarro's investigations and pointing them in the right direction.

What do the spirals in True Detectivemean?

At its most surface-level, the spiral symbol physically connects the murder of Annie Masu Kowtok with the frozen scientists, including Clark. Beatrice's decision to mark one of Annie's murderers with the sign meant Danvers and Navarro linked their cases, but it also led them to discover Annie and Clark's connection and helped them find the actual crime scene.

But there's a deeper spiritual thread to the spirals. The importance of the spirals as a warning sign seems to be deeply connected to Iñupiaq tradition in the series — Tagaq's petroglyph, Annie's tattoo, Kenny's memory of his grandmother. As Rose says, it's an ancient symbol, which means historically there are loads of interpretations. Annie saw the symbol in recurring dreams then had it tattooed on her body, which feels like a bleak premonition of her death, and Clark became obsessed with the symbol after her death, so perhaps he felt warned of his own doom amid his guilt.

But this is also True Detective, with its insistence on a "time is a flat circle" philosophy and the inevitability of events. The spiral (which is almost literally a flat circle) could be a marker for the never-ending cycle of violence, only this time, it's one that has an actual end.

How to watch:True Detective airs Sunday nights on HBO/Max at 9 p.m ET/PT.