"The book follows Skylar, Rachel, Caitlin, Beth, and Bethany, five immortal sisters who, over the course of a thousand years, attempt to learn the purpose of their own existence while hunting down the worst criminals this world has ever seen," according to a press release. "They’ve faced the likes of Jack the Ripper and the Nazi scourge, but as a new enemy arises to threaten the sisters’ survival they’ll soon learn that immortality doesn’t mean forever."

After seeing first-hand what young girls went through, he got the idea to create "invincible girls who would be invincible to that sort of thing."

In the process of writing the novel, he interviewed over 100 young women to get a description of their day-to-day lives and what issues faced them.

Stark said girl power and redemption are the two overarching themes of the novel.

"No matter who you are as a young girl you should embrace it," Stark said. "No matter who you are you can always achieve redemption and choose your dreams and goals. Even if you're getting bullied and the worst things happen to you, there's a bright future out there for you."