You decide to go to a party alone and meet a girl

Four girls decide to prank Anna Xie, a girl who has hurt them one way or another. She dies after the prank goes wrong. Over one year later, Joanna, Elise, Bethany, Golden and a new addition to the group Melody, are all receiving black roses and text messages from an account called Occisor on Snapchat who is targeting them and everyone they love. This person seems to know exactly what happened to Anna that night and a bunch of other secrets. Who is Occisor? Why is this person after them? Will they find out who the killer is and make it out alive? Or will the five girls suffer at the hands of psycho and face a cruel end?