Libby is a well known assassin and is always taking the most dangerous jobs there along with her group. Jack, Zack and Allison where her three close friends in her work and that night they where given a mission to go a abandoned power-plant where a mafia gang was meeting up at along with another one (your oc is the leader of one of the mafias). They all had mask just in case as they reached the power-plant "alright remember quick and quite" Libby says as they nodded slightly.
