Undead (the part)

Y/N is a 20 year old that's supposed to be dead but suddenly comes back from the dead and she goes to this criminal academy, she meets someone there named Felix they become friends one day all the good students of the academy ( the advanced ones )that know how to deal with criminals and stuff disappear then the next day Y/N receives a letter saying ''your next'' in blood. Y/N and Felix try to solve the case and lots of plot twists get untwisted