Oskar, the big black Shepard of the horse farm, loves to be in the water more than just about anything else. So when Tine, Alex, and Ina head to the lake for a picnic by the water, it's no surprise that Oskar wants to come along. What the girls do find surprising is Oskar's unusual behavior once they arrive at the lake. Before they can attempt to calm him down, the big dog disappears. Unfortunately, finding Oskar is just the beginning of their problems.