Twelve-year-old Harold, with his mother, comes to the lake before moving far to the West. He goes into the water and calls his beloved girl named Tally, who drowned some time ago. Harold yearns for his first love and tries to return it. He believes that Tally hears him, but the lake does not allow her to answer. Harold builds half the sandcastle, the same as they used to build together. He tries to lure Tally out of the lake so that she can help him complete the sandcastle to the end. But the lake is merciless to his attempts and destroys his hopes, as the waves destroy the sandcastle. Ten years later, Harold and his wife, Margaret, come to the city of his childhood, where he suddenly receives an answer to his call.