A man is found burned to death inside of a car. Detective Sang-Gil (Song Kang-Ho) and his co-workers investigate the scene. Sang-Gil doesn't want to take the case, because it looks like a simple suicide case and won't help him get the promotion that he desperately wants. Furthermore, rookie female detective Eun-Young (Lee Na-Young) is selected as his partner for the case.
Later at the morgue, Eun-Young discovers a dog bite on the burned corpse. As Detective Sang-Gil and Eun-Young investigate further they discover a trail of drugs, child prostitution, and a lethal wolf-dog all involved in the case. Detective Sang-Gil and Eun-Young keeps their discoveries to themselves as Detective Sang-Gil hopes to crack the case and get his promotion. Soon, another murder victim is discovered having dog bites on his body. Can Detective Sang-Gil and Eun-Young unravel the mysterious case before more people are killed?