The Tegen Cave by Inge-Lise Goss
On the run from her old flame’s organized crime family, Sara Jones hides in Billings, Montana, and finds a new boyfriend. But when people around her start dying from poisonous spider bites after she receives a mysterious package with a spider concealed inside, she worries that the crime family has found her. Life takes an even more bizarre turn when she seems to be not only immune to the spider venom, but also surrounded by a sinister group of people using spiders to incapacitate their prey. Even her new boyfriend starts acting suspiciously. Just who can she trust?
Then to make matters worse Sara’s twenty-fifth birthday approaches, and her dark heritage begins to emerge. She is forced to make a life-or-death decision. And somehow, she must find a way to deal with the crime family.