Sininen enkeli vividly depicts the colorful upswing of the 1980s in Helsinki, where money grows on trees, convertibles guarantee the thrill of speed and the solarium is the new sun. Marko Hyyryläinen, who hides his country background, arrives in the city and wants his share of money and love.
A mural painted with blood is found on the wall of Pasila train station, which depicts Finland's best-known serial killer Lasse Maasalo. The text in the mural, “Making the world a better place”, is linked to a voting circulating in social media, where people can vote for persons that world would be a better place without. Soon the first body is found and Sorjonen must find the person who has named himself as The Judge.
Serena Rapper gets a strange prediction: a genius has been born to her immediate family. When Serena finds a drawing Ricky has made, she is certain that Ricky is Vincent Van Gogh reborn. She decides to show Ricky's drawing to the intendant of the Art Museum. At the same time, a sketch of one of Van Gogh's paintings is found in Finland! This discovery starts an exciting chain of events, and in the end, the janitor of the Art Museum, a keen amateur detective, helps Ricky and Nelly to solve the mystery.