An unidentified man is found murdered in Costa del Sol in Spain, but his tattoo of the Oulu pro hockey team points to his Finnish citizenship. Detective Hilkka Mäntymäki"s peaceful time in Finland gets interrupted when her old colleague Luisa Salinás asks for her help on the investigation.

Andrés Villanueva"s visit to Finland takes a new turn when he starts to assist Hilkka and Kimi in the investigation. Promising young athlete Timo receives unwanted information about his health. At the same time, a young African couple gets trafficked to Spain by a shady group of people.

Hilkka, Andrés, and Kimi head to Spain to pursue their inquiry. Finnish entrepreneur couple Sohanna and Petteri have some strange connections that rouse suspicions. A horrifying discovery at a water treatment plant makes it clear that the case is bigger than it first appeared.

What business could Police Chief Armando Coréa have with the murdered man from Oulu and real estate agent Sohanna Lahti? Luisa conducts a private investigation into Coréa"s dealings behind the scenes; what she discovers causes plenty of concern.

A clue prompts Luisa and Hilkka to launch a wide search to locate the suspect. However, the case seems to lead them in many different directions, and no one is willing to talk. Luisa must face an unpleasant person from her past who makes things difficult for her.

Melilla and Andrés decide to return to a city where he used to be an undercover operative. Hilkka and Luisa concoct a plan to force the suspects to make a move. New discoveries only lead to more desperation, and neither of them realize that Hilkka may be in danger, too.