Sara Shephard is something of a literary celebrity. The Downingtown native’s young adult series of books, Pretty Little Liars, is hugely popular (and the basis of a television show that will wrap up its seventh and final season next year). Set in the fictional Philadelphia suburb of Rosewood, the books feature savvy, stylish teens getting into and out of trouble.

Last year I had the pleasure of speaking with her about her work, at which time she mentioned a forthcoming book, a mystery, the first in a new series. That book arrived this month. The Amateurs tells the story of several teens to who band together to reopen and investigate an unsolved murder case. Each brings his or her own difficult history along, and the book is as much about the relationships among the group members, and the building and unraveling of bonds of love and friendship, as it is about crime-solving. But, being a mystery, the book also has a large share of twists and turns, ending with what Shephard calls the "twistiest twist" of all her books.

The Amateurs,  the new book by Sara Shepard.

Shepard has been travelling a lot to promote the book. "I've been going to a bunch of schools and bookstores," she says, "and recording my life on Snapchat and Instagram. Doing all the fun social media stuff." And while the travel can be hard, especially leaving behind her children for stretches of time, she loves meeting her fans.

And who are these fans? "There's a range now," she explains. "There are people who started with Pretty Little Liars 10 years ago and have grown up with the series. There are fans who watched the show on TV and came over that way. The ages are all over the place, and there are different demographics and ethnicities and interests, guys and girls. More girls, though." She loves her readers. "I like writing YA [young adult] because it has very rabid fans. You get a lot of enthusiasm. You get screaming people who want to take millions of pictures. They make art projects for you and write you letters."

Shephard understands the excitement of reading a book and then meeting the author: "I wish I would have been able to talk to authors when I was a kid." She tries to respond to her fans' outreach as much as possible ("I try to write back to everybody. It's hard"). She believes it's important though: "If I had gotten a note back from an author when I was a kid, I would have just lost my mind!" And from the questions her readers ask, she knows they are interested not just in the books but also in the writing process. "They are deeply involved in these books," she says, "and trying to figure out how a writer's process and mind works."

She is excited about The Amateurs and its characters, who are trying to take control of their lives and the situations in which they find themselves. She’s particularly fond of Seneca, the female lead: “There’s a very strong female boss who is the smartest and toughest. She’s complex. I loved creating her. She’s clearly the leader. Pretty Little Liars didn’t have a leader.”

She's also excited about the writing life she has been able to grow and sustain for all these years.  "I'm very happy to have a job where I enjoy doing it every day," she says. "Being a writer is a 24-hour job. You're always thinking about various things that aren't working in your story, or new ideas. Even if I'm doing other things it's always in the back of my mind. I don't let it go at the end of the day. Still, I'm thrilled I'm still doing this after 10 years."