Jin Nga is a 32 year old archeologist with a sad past. He lost his little sister when she foolishly summoned a demon in their family homes basement at 13. He tried to save her but ended up losing her and his arm in the process. That all occurred when he was 20.
Over the span of the next 10 years Jin dedicates himself to figuring out what book his sister summoned the demon from and where the book originated. On an archeological trip in Peru he finds an ancient prosthetic arm that forcibly find its way to adhere itself to Jin and his residual limb, destroying the dig site and everything with it. It isn't until a year later when Jin finds a scrap of text that talks about the prosthetic and its capabilities. Jin learns that the limb itself can be a vessel for lost spirits...and can trap demons.
He returns to his family home and attempts to save his sister's spirit from the scorched circle in the ground, but instead captures a minor demon, Phensulo. Now Phensulo is trapped, forced to help Jin, until Jin can find the correct text that will tell him return Phensulo to Hell and rescue his sister's soul once and for all.
Enters Jin's venture of the "Wayward Paranormal Investigation" business. He is able to gain access to ancient texts, that would otherwise be unaccessable, as well as help other people who have been experiencing paranormal encounters, and possibly prevent them from harming anyone else in the hopes that what happened to his sister can never happen again.