Oh, thats not LD+, thaat must be LD, Mystriya is only avalable in LD. She is not yet in LD+ also, have you tried doing the tower lab quest by getting infected by encounters in a military base then going to the lab to get rid of them? then after that, defeat mystriya thenask her for help. then when you both get in the tower lab, SAVE often, then defeat the lab quest, go out of the lab, go to the military base, defeat mystriya, then ask her where linda went then she should lead you deeper in the base, find her then continue from there. ( •_•)