It's Kill or Be Killed.
After ten years of hunting together—and almost as long living together—Asphodel put a bullet through Oleander, breaking her heart literally and metaphorically. But Oleander is resilient, and poisonous. And her former collaborators, deadly assassins all, are gonna feel her wrath.
Oleander's Kiss is the first installment of a four-part series. It contains mature content that may be upsetting to some readers.