I Pinky Swore with Death

Adeline Collins was born with the gift to see spirits after they leave their mortal vessels.This gift also has allowed her to see Death himself. He rarely ever shows up in the mortal realm but when he does he barely notices Adeline. Only on select occasions has she seen him throughout her life and the instances were always few and far between.
However, on her 22nd birthday Adeline's friend is violently murdered and their spirit enlists Adeline's help to find out who did it. Unfortunately Adeline doesn't get to even look into the case before she is also murdered, supposedly by the same man.
This is where she officially meets Death and makes a deal.
Send her back to the living so she can find her and her friends murderer and she will use her ability to help Death in any way he needs. Death agrees on one condition, she can't contact anyone from her old life.