A frozen body is found on the boundary stone right on the Austro-German border, as if propped up for some pagan ritual. Shortly after the disparate investigation duo, police inspector Gedeon Winter from Austria and commissioner Ellie Stocker from Germany, have joined up on the case. The killer has sent audio messages to the press. The unsettling recording from the victim taken before her death, as well as intricate elements of the crime, make the investigators suspect this murder is merely the beginning of a greater scheme.

A German entrepreneur has been killed in Austria. His secret lover was found comatose on a ski piste late at night, drenched in blood. Evidence links this case to the first murder. Ellie, the optimistic and confident investigator from Bavarian Berchtesgaden and her Austrian counterpart Gedeon, the nihilistic cynic from Salzburg, realise they are dealing with a highly intelligent and cold-blooded killer. His victims seem to be symbols for our modern, anonymous society that deserves to be punished.

Tipped off by the killer's horrific photofit, the investigators unearth the Krampus legend - a symbolic creature infamous for punishing the naughty and unworthy. This leads them to Sebastian Brunner, head of a rural sect, whose books on the end of civilisation seem to have inspired the killer. Through the cult leader, Ellie and Gedeon manage to contact the perpetrator via the internet. This achievement, however, can't stop the murder of a YouTube starlet on a lake near Salzburg.

In a joint effort with cultist Brunner, Ellie and Gedeon try to set a trap for the killer. For this plan to work, they have to overstep legal boundaries. Trying to gain the trust of the killer, they feign a copycat murder, hoping their target would be lured into reaching out to Brunner. Meanwhile, Ellie has started an affair with her superior, whereas Gedeon has been haunted by his shady past as a corrupt narcotics cop.

The demanding investigation has affected Ellie in a major way. The German policewoman and the Austrian cop bicker and fight constantly. While her positive life views get dulled and stunted, Gedeon's initial indifference changes into an obsession for cracking the case. After one lead brings them to yet another dead end, they have to start again from the top. They dive into case files of unsolved murders over the past years, hoping to find any trace of the serial killer.

A fierce detonation blows up a fashion outlet mall in Salzburg. Despite Ellie and Gedeon trying to evacuate the building in time, a child is fatally wounded in the explosion. The deadly assault riles up the general public, whereas politicians and the media demand fast results from the police. In Austria, Gedeon has to fight to stay on the case. In Germany, Ellie loses trust in her superiors more and more. After the Krampus Killer has leaked details of her affair with her boss to the press, her life collapses.

When the international press conference on the bomb attack gets interrupted, everybody suspects that something major must have occurred: A man wearing a Krampus mask has been shot during a gunfight with the police. It looks like he's the sought-after Krampus Killer. Neither his superiors nor politicians or press want to believe Gedeon's theory that this must be a copycat riding the real killer's coattails. The general demand for a success after months of fear and mayhem is simply too great.

In the Austrian region Steiermark, a decayed female body is found in a buried wooden box. When the victim is identified as Malica, Gedeon senses the Krampus Killer has struck again. At first, nobody shares his suspicion. But his reinvigorated eagerness convinces Ellie to pick up an unofficial investigation on their own. They find out that the Macedonian victim, Malica, has been reported missing back home.

One year on from the events of the Krampus case, junior police officer Yela Antic finds herself working under the guidance of Ellie Stocker.

Gedeon wakes from a coma only to receive unwelcome news from his medical team. Meanwhile, Ellie struggles to hide the extent of her trauma. A new case comes in from Austrian investigators—prompting Ellie to pass it to new colleague Yela.

Yela travels to Austria for the investigation, and is greeted by Riffeser and Christian, who are both assigned to the case. Feeling frustrated by a lack of progress, Yela decides to turn to a familiar face for help, with promising results.

After more than a year of silence, the killer strikes again. But when an outsider throws Yela and Gedeon’s investigation off track, it comes with serious repercussions. Undeterred, Yela takes her hunt dangerously close to the killer.

A grim discovery is made about Yela, prompting Ellie to return. Meanwhile, the team works to trap the murderer once and for all. But when their plans are foiled they begin to suspect there’s a mole within their ranks.

After a fourth body turns up, Ellie and Gedeon’s investigation leads them to a secretive and elite hunting club. But when the members rebuff police attention, the pair are forced to take unethical measures as they zero in on the killer.

With a fifth woman within the killer’s grasp, it’s a race against the clock to unveil the murderer’s identity. Both Gedeon and Ellie battle to hide their struggles as their prime suspect slips through the pair’s fingers.

Determined to stop the killer, Gedeon and Ellie believe they’ve found the key to bringing the whole case to a close. But when the pieces don’t quite add up, Ellie pushes further, revealing shocking truths about her partner and friend.

The murder of her colleague Yela Antic does not leave Ellie alone: she wants to call Gedeon to account for the theft of the murder weapon. Meanwhile, Gedeon delves more and more into his past.

A burned woman's body is found in Austria. Instead of Ellie, her new colleague becomes a liaison officer in the German-Austrian Soko. Gedeon distrusts his colleague Rafael Lutz.

Ellie and Gedeon are working together again, but in secret Gedeon is looking for the artist Oskar Koschlick. After another murder, Ellie receives an important clue from journalist Charles Turek.

While new evidence leads to a Reichsbürger, Gedeon continues to search for Koschlick. In the process, he is increasingly plagued by hallucinations. Ellie and Rafael get into an argument.

Another murder points to a pattern - the perpetrator profile fits the main suspect. At the Gössen construction site, activists and police fight each other. Gedeon comes across a legendary figure.

A supposed motorcycle accident on the pass road leads Ellie and Gedeon to a ritual spot in the forest. They learn more about the legend of the Schinder Jackl. Turek makes a confession to Ellie.

During an operation in the forest, the police are confronted by a mysterious man who does not reveal his name. What does he have to do with the murders? Gedeon gathers his last strength to find Koschlick.

A house search ends disastrously and still the officers do not know how the suspects and the murders are connected. To solve the case, Ellie and Gedeon go beyond their limits.