WHEN HAN YU-JIN, a 25-year-old law school hopeful, wakes up one morning covered in blood with no memory of the night before, he backtracks the lone set of bloody footprints from the foot of his bed down a hallway and discovers at the bottom of a flight of stairs the murdered body of his mother. His first thought is that the killer is still in the house, and his second theory is that thieves broke in and he interrupted her murder and experienced one of his seizures after scaring them off (nothing seems to be missing), but he stops himself from calling the police because he can’t explain his own condition. He knows it looks bad, doubly so when he hears the news reports about a second murder victim in his neighborhood that same night, a young woman with a slit throat like his mother’s. He suspects that one killer is responsible for both victims and reluctantly opens up to the possibility that maybe he is that killer. Over the next couple of days, Yu-jin sets two equally difficult tasks ...