The movie centers on two siblings, an 11-year-old boy named Chan-yi (Yoo Seung-ho) and his little sister So-yi (Kim Hyang-gi). Abandoned by their mother, they are left to survive on their own. For his sister's 6th birthday, Chan-yi decides to give her a dog. He sneaks into a house of an old couple and steals a newly-born puppy, which she's been longing to have. Even though they are poor, they were happy. But everything changed after a tragic accident; So-yi died. Chan-yi blames this on his dog and finds his way to his mother, not realizing that the dog was the only true family that would never leave him.