Kim Seong-geun (Jung Jae-young) is sunk in debt and his life seems completely hopeless. He jumps off a bridge on the Han River and reaches the banks of Bamseom, which is just below the bridge. After searching the island, he finds that it is full of vegetation and surrounded by the city, but too far away to scream and he is unable to swim. He finds a rowing boat in the shape of a duck and begins to enjoy living on the island - free of debt and worries about life in the city - although it is not easy.
As he learns to survive on the island, his scream for help scrawled in the sand is seen by Kim Jung-yeon (Jung Ryeo-won), a hikikomori who sees him as he engages in his nocturnal habit of photographing the moon. They soon start exchanging messages, with Jung-yeon venturing out of his home at night to throw bottled messages on the island, and Seong-geun writing his answers in the sand. Seong-geun also manages to grow crops to prepare noodles for a packet of instant noodles from jajangmyeon.
A torrential storm arrives, destroying Seong-geun's farm and sweeping away the belongings he has collected. He is found by a group of workers sent to clean up the garbage on the island and forced to leave. Seong-geun boards a city bus to jump from building 63. Jung-yeon, who, after overcoming his anxiety and running desperately across the bridge to find him, manages to reach his bus after civil defense training paralyzes him. She boards and introduces herself to him.