1990. Under the glow of a full moon, a sadistic murder is committed on Nordkoster island - a young pregnant woman is buried in the sand, so that she slowly drowns as the tide rises. 25 years later, the case remains unsolved. Olivia Rönning is assigned the case to work on, as cold-case training at the Police Academy. Olivia becomes obsessed with the murder when she discovers that her father, who died several years ago, worked on the original investigation. She soon realises that she has to find the lead investigator, detective Tom Stilton. There's only one problem - he has disappeared off the face of the earth. Tom Stilton is homeless now and does not want to be reminded of his old life or an old, unsolved case - he has a hard enough time just surviving. Horrifying videos start showing up online, in which homeless people are brutally assaulted, and one of Stilton's friends is attacked. Written by Mattias Thuresson

Olivia is totally engrossed in the Beach Case, but doesn't have any luck finding Tom Stilton. She goes to Nordkoster island, instead, to visit the scene of the murder. When she comes to the beach at Hasslevikarna bay, a man appears with a rolling suitcase. Who is he and why does he behave so strangely on the deserted beach? Stilton finds out through Situation Stockholm that Olivia is looking for him, but he is completely uninterested in being in contact. He has other problems. His friend has survived the assault, but Stilton and the rest of Stockholm's homeless live under the constant threat of becoming the next victim. Meanwhile, the police investigation of the attacks is dragging, partly due to the fact that the lead investigator, Rune Forss, an old enemy of Stilton's, is not very engaged. Written by Mattias Thuresson

Stilton finds his friend Vera severely beaten and is devastated. He decides to pull himself together and try to find the perpetrators himself to get his revenge. Olivia has received information about a former escort, Jackie Berglund, in connection with the Beach Case. She decides to investigate her further. She contacts a journalist who interviewed Jackie a few years ago, Eva Carlsén, for advice on how to approach her. Eva warns her against digging around too close to Jackie. Linn Magnuson, CEO of mining company MWM, receives a prize for being the year's best Swedish company doing business abroad. During the prize ceremony, she gets an unsettling phone call which she realises can crush both her and the company. Olivia finally finds Stilton. Their first meeting doesn't go very well, but Stilton gives Olivia some answers to her questions.

Olivia continues to look for information about Jackie Berglund, but goes a little too far when she visits Jackie's store Odd and Right. Jackie has already heard that a young woman has been digging around in her past, and she quickly realises that it is Olivia. Olivia's mother tries to tell Olivia to take it easy with her investigation into the Beach Case. She doesn't want to see Olivia become as obsessed as her father was. Tom Stilton slowly starts to get in shape for his hunt for the people who killed Vera. He contacts his former snitch, Minken, to help him find them. Minken's tips lead to Stockholm's shady underworld and Stilton comes dangerously close to Vera's killer. Linn Magnusson agrees to a secret meeting with her old business partner, Nils Wendt. She gets a cassette tape with a recording of an incriminating phone call. Nils says that he is looking for revenge for the past. Linn's entire life hangs in the balance...

Children find a car in the water where they are swimming. Inside the car is a dead man. Stilton's old colleague and ally, Mette Olsäter, takes the case and quickly starts a murder investigation. The dead man, Nils Wendt, has been missing since 1987. Where has he been all these years, and why has he turned up now? Olivia tries to take it easy after the attack. She is certain that Jackie Berglund is behind it. But she is more worried about her cat, Elvis, who she hasn't seen since. When she watches the news about the dead man in the car she immediately recognises Nils Wendt - the man she saw on the beach in Nordkoster. She contacts Stilton right away. Mette Olsäter goes to see Linn Magnusson, who feigns shock at the news that her old business partner, Nils Wendt, was murdered. Linn doesn't tell her that he recently contacted her, and that they met in person.

Olivia finally gets in contact with the man who witnessed the beach murder as a child, Ove Gardman. He tells her that he met Nils Wendt in Costa Rica. Olivia gives this information to Mette Olsäter, who decides to send Abbas - a friend to both she and Stilton. She wants to see if he can find anything that can explain Nils Wendt's murder, and if there is any connection to the murder in Nordkoster. The police manage to get Nils Wendt's mobile phone working and find that his last call was to Linn Magnusson. Linn realises that she has to find the place where Wendt has been hiding quickly, so she can find the original recording of their phone call - the evidence that would ruin her life. Olivia gets a hair clip from Ove Gardman with several strands of hair stuck in it, which he found on the beach on the night of the murder. Olivia gives it to Stilton hoping that he will pass it on to his ex-wife, who works in Forensics. Could there be any DNA left?

Abbas finds Nils Wendt's house in Costa Rica, as well as his friend, Bosques. Bosques tells him that the woman who was murdered on the beach in Nordkoster was Adelita Rivera and that she was in a relationship with Nils Wendt. Abbas also gets a bag of material that Wendt left behind, in case he didn't return. Mette realises that the investigation of the murder in Nordkoster and Nils Wendt's murder are now one and the same. Linn Magnusson has sent people to look for the evidence Wendt left in Costa Rica. They know that Abbas is there too, looking for the same things, but they don't know who he works for. But Abbas has worked faster, and Linn orders them to stop him by any means necessary. Stilton tells Olivia that the strands of hair from the hair clip on the beach did not belong to the victim. But Olivia won't give up, and gets help from Stilton's former informant, Minken, to continue the search. She has a definite sense that Jackie Berglund is involved. Could it be her hair in the ...

Stilton's ex-wife visits him in the trailer. She wants to see how he is living, as well as let him know that she got a match for the DNA from the hair clip - it is Jackie Berglund's. Mette immediately calls Jackie in for questioning and wants Stilton to participate. After the interrogation, Jackie sees Olivia waiting outside. This worries Stilton, because he knows that Jackie will stop at nothing to protect herself. Abbas is on his way home from Costa Rica, heading directly to a meeting with Mette, Stilton and Olivia. What he doesn't know is that Linn Magnusson is also impatiently waiting to get her hands on what he found on his trip. She has a man waiting for him in the arrivals hall at the airport, with instructions to get Wendt's material at any price. Olivia goes to pick up Stilton and gets a shock. The area is cordoned off and Stilton's trailer is on fire.

Abbas manages to deliver all of the material to Mette and her group. When they listen the recorded phone call between Linn Magnusson and Nils Wendt on the cassette tape, they go straight to Linn Magnusson's house. But they get there too late. Olivia is frustrated that they haven't come further with the Beach Case, but decides to get revenge on the person who killed her cat. She is certain that she knows who it was. Stilton visits his burned-down trailer, where someone tried to kill him the night before. He realises that the police don't intend to spend any time on the investigation of Vera Larsson's murder and the assaults on homeless people. He will just have to take care of it himself. Olivia sorts her laundry and in the pocket of a jacket, she finds a picture that Stilton drew - an earring that was found in a coat that belonged to the woman on the beach in Nordkoster. Suddenly, Olivia realises where she has seen the earring before.

Mette gathers everyone at the police station. Stilton and Olivia are there as well. The puzzle pieces start to fall into place. They have identified the person who had the earring - the earring from the murdered woman's coat in Nordkoster. Now they are just waiting for a conclusive DNA analysis. They have also identified a new witness who was in Nordkoster. Mette calls in a new suspect for questioning. But how is the murder in Nordkoster connected to Nils Wendt's murder? And what was the motive? Stilton and Olivia come closer and closer to solving the Beach Case. But there is one thing about the case that Stilton has kept to himself, that he now feels he has to reveal - something that will have unimaginable consequences for Olivia.