Indie musician Dong-hoon and cartoonist Jae-hee broke up a year ago. The former couple meet again after the death of the cat they owned together, and go on a night's trip to hold a funeral for their pet.

Hyunjin, a test taker, moves into an old apartment. There are strange sounds from next door where a strange boy named Hyunggu lives. One day, Hyunggu and his mother are cruelly murdered.