This is another part of the adventure known favorite characters from the books of Martin Widmark and Helena Willis about a couple of young detectives Valleby. This time, Lasse and Maja will have to solve the mystery of the disappearance of the magnificent ancestral jewel, Stella Nostra. Feuding Italian families, their history and hanging in the air a new conflict - detectives will work in difficult conditions.

In a small quiet Swedish town Valleby last feverish preparations for the wedding of two young owners of a local cafe Dina Panini and Sarah Bernard. Young detectives Lasse (Anthony Scardina) and Maja (Amelia Natkaniec) help their friends in the preparations for the ceremony. But when relatives come to Valleby bride and groom, Panini from Dina and Biscotti by Sarah - it turns out that among the warring each other Sicilian Mafia families.
At the head of each of them there are two real godmothers: sharp as pepperoni Bresaola (Agnieszka Dygant) and devastatingly sweet Clara (Margaret Kożuchowska). Wedding Dina and Sarah hangs in the balance. The situation is all the more heat that the safe is lost precious jewel of a family - a diamond Stella Nostra. Is Lassemu and Mai manage to prevent war mafia in a quiet yet Valleby and bring to the wedding of Sarah and Dina?