For the past two decades, fans have wanted to know what happened to the characters in Alice Hoffman’s 1995 novel, Practical Magic, which was turned into a film starring Sandra Bullock and Nicole Kidman.

“[Practical Magic] is a lot of people’s favorite book, and many also loved the movie. I thought it would be great to go backward in time with it, not forward,” Hoffman says. She wanted to look at the aunts to find out how they came to be who they were.

In order to write the prequel, The Rules of Magic (Simon & Schuster, Oct.), Hoffman had to research New York City in the 1960s. “I felt like I was time traveling. It was fun to be back in New York [then],” Hoffman says. “I did a lot of research about Greenwich Village, and I feel I could now lead tours around Washington Square Park. Everything was so new and unique—fashion you’d never seen before, music you’d never heard before. It was also a time when people were into looking at different philosophies and cultures, different ways of thinking, looking at spirituality, astrology. People used drugs to expand their minds and thoughts about what reality was, so for me it seemed like the perfect setting for magic.”

As Hoffman explored the ’60s, she saw parallels with what’s happening in the world today. “There were a lot of people back then feeling like outsiders, being different and disapproved of, just like today,” she says. “There’s a similar kind of realization and worry about what would happen if there were a war. Back then, and now, there were fears about the government, and young people similarly are really nervous that there’s not a future for them.”

The Boston-based writer has appeared at BookExpo several times, and looks forward to returning. “It’s a great experience because I get to see so many people, many of whom I know from Facebook, but have never met in person,” she says, adding, “BookExpo is such a great way to get your book out there and connect with readers and bloggers and people you wouldn’t ordinarily meet.”

Today, 12–12:45 p.m. Alice Hoffman will sign at the Simon & Schuster booth (1420, 1421).