How do you follow up one of the most talked-about best-sellers of recent years? If you're Sara Gruen, you simply follow your passions.

Gruen, author of the aforementioned beloved novel "Water for Elephants," as well as two previous novels, "Riding Lessons" and "Flying Changes," used her long-time interest in language acquisition among great apes as the inspiration for her newest work, "Ape House."

"Ape House" is informed by several visits to the Great Ape Trust in Des Moines, Ia., where Gruen met and communicated with a group of bonobos through American Sign Language. She relied on these encounters in writing the story of Isabel Duncan, a researcher at a facility that houses great apes; John Thigpen, a reporter assigned to profile the lab; and, of course, the apes themselves, who are severed from the facility following an explosion.

Gruen spoke to the Times last week about her new book, her approach to her craft, and the advice she has for aspiring writers.

Q. Talk about your creative process and how you approach your work.

A. I really hate outlines ... When characters decide to take a different turn you really (can't let them if you're working with an outline).

I always have an idea of what the crisis of a book should be about ... and I try to make things really complicated (so that it's a challenge to work my way to resolution).

My method does mean that I have to do more editing and rewriting than most people.

Q. What has been your favorite character to write and why?

A. I have different favorite characters for different works-Walter and Rosie in "Water for Elephants"; I like Harriet the dog (in "Riding Lessons")...For "Ape House," I really had fun with John and my heart really broke for Isabel; she's really the scraped nerve of the book.

Q. You write so vividly in "Water for Elephants" about circus life and elements of the Great Depression. How do you approach your research and when do you know when it's time to stop researching and start writing?

A. With the circus stuff I was starting from absolute zero. I hadn't even been to a circus. I went to various circus archives ... I really just wanted to get a feel of the look, a sense of the colors and the costumes, and so on ... I realized I was ready to go because no one cared what kind of lug nut was used on the train.

With the apes I had to have a sense of them ... I had to have been with them enough and to have read all of the tales of language acquisition ... I had to get a really good background.

Q. "Water for Elephants" met with such critical success and a warm audience reception. Were you nervous about following it up?

A. Of course ... Actually, "Water for Elephants" had mixed reviews at the beginning ... I don't think anybody expected it to do what it did. It was word of mouth and booksellers and book clubs that made it happen.

Q. What were some of the most astonishing things you learned in researching great apes for your new book?

A. I did not expect them to speak in full sentences and I did not think they would use tenses ... I knew that they were language-cognizant apes, but I didn't know the extent of it.

Q. What were some of the unique challenges of including apes as characters in "Ape House"?

A. I had wanted originally to write in the first person … but it became very clear that I could not … so I changed the voices so that everything is from a close third … I was trying very hard not to anthropomorphize them.

Q. What do you hope people will take away from this book?

A. I would never ever want to tell people what to think, but I really hope, if they're not aware of this other world, that they'll become aware of it ... I really hope they just enjoy the storytelling and I hope I've provided a bit of fun escape.

Q. What advice would you give to aspiring writers?

A. Make sure that you write every day. Set aside your writing time and make it sacred. The only thing you can't edit is the blank page.

Sara Gruen will discuss her new novel "Ape House" on Thursday, Sept. 23 at 7 p.m. in Hubley Hall at the First Congregational Church of Madison, 26 Meetinghouse Lane; presented by R.J. Julia. Tickets are $10, $5 of which may be used toward the purchase of the book. For more information and to purchase tickets, call 203-245-3959 or visit www.rjjulia.com.