Oskar and Patka, fearless adventurers, set off on a seaside vacation, not expecting that an incredible investigation awaits them there! When they secretly find an encrypted map leading to a legendary treasure from adults, their vacation turns into a mission full of twists and turns. The young detectives want to outsmart their suspicious guardians and secretly set off on the trail of the treasure, but everything is complicated by the unexpected disappearance of Patka. Oskar has no intention of giving up. Together with the famous actor Bruno, the crazy aunt Maryśka, the energetic Kaja and the clumsy plasterer Straszylas, he sets off to rescue them. The Tri-City is full of secrets, and discovering more traces leads the team into increasingly dark corners, where surprising obstacles, opponents operating from hiding and the question: what is the mysterious Żôłti Kam really? Will Oskar and Patka dare to face the dangers hidden in the seaside secret and solve the detective puzzle?