After a mafia boss was secretly assassinated, his spirit descends to the gates of the afterlife and was denied access to enter the afterlife; because the worker there did not get a record of how he have died. However, the worker allowed him the chance to go back down to Earth as a spirit to find out who have caused his death, but there is one requirement to this though. He must work together with a man in the past who he have killed his whole entire family in order to investigate his death, since because he's only a spirit now and doesn't have a body.

The mafia boss is only a spirit now, so he can easily go anywhere he wants and not get spotted by anyone at all. However, other than the man that he is supposed to work with in order to investigate his death, no one else can hear or see him at all. Therefore, he cannot communicate with anyone else, due to him being a spirit only. He would need the man's help on his investigation about his death, due to the man being able to talk with people and communicate with them in order to obtain information about his death.

The mafia boss and the man would have to work together by using each others' unique abilities; in order to help the mafia figure out how he have died.

However, would the man be willing to help out someone who have killed his whole entire family in the past?