At the turn of the century in 1999, Ma-jin is a snobbish detective struggling with chronic poverty. One day, his partner, Eun-rak, returns to life after losing his life in an accident while raiding an affair. However, the body of the deceased Eun-rak is inhabited by a mysterious creature claiming to be a "Biological Vault." It makes an offer Ma-jin cannot refuse: if he extracts it from Eun-rak's body and sets it free, it will hand over the illicit funds inside15.7 billion wonto him. The problem is, to open this monstrous vault, "scorching physical stimulation" that sends shivers down the spine is absolutely necessary! With money in desperate need, his partner acting strangely, and dangerous pursuers after the 15.7 billion won closing in, it is a volatile situation. Will Ma-jin be able to safely "decipher" this loud and audacious Biological Vault and hit the jackpot for a life-changing turnaround?