Would there be grades even for blood? A father and son, homeless, wander from motel to motel, selling collected blood to vampires. They always receive a C grade. Hae-don, after asking for the secret from a man who received an A grade, becomes troubled. Eventually, he decides to draw his son's blood. What grade will his son's blood receive? Is a person's status predetermined from birth, unchangeable through effort? The image of Hae-don and his son walking against the backdrop of high-rise apartments continues to linger in memory.