The action takes place in Piran, where three children meet. An SMS message was sent to the wrong number triggers a series of events in which children go through various adventures and puzzles related to Piran. The antagonists of the story are bandits who are looking for treasure, but they are overtaken by children who are more skilled in solving the keys that lead to the treasure. The children are the first to find the treasure, which is actually a collection of letters between the famous violinist Tartini and Stradivari, a violin maker who through correspondence provided him with support and advice on improving violins.

A detective runs into his violent brother he hasn't seen in twelve years. While trying to help him, his actions trigger repercussions that will shake their lives to the core.

Nikola spends the summer caught between the violence of the streets and the fragility of his broken home, where he must parent his own mother. He struggles to find a place where he does not feel completely alone.