After writing six YA novels, bestselling author Morgan Matson makes her middle grade debut with The Firefly Summer, a captivating mystery blended with an emotionally rich family story. Eleven-year-old Ryanna accepts an invitation to stay with her estranged maternal grandparents in the Poconos at their nonoperational summer camp and discovers a large and vivacious extended family, as well as a treasure map created by her late mother that may save the camp from being torn down. Matson spoke with PW about writing for younger readers, how her own summers in the Poconos inspired the tale, and how her theater background helps her when crafting characters.

What drew you to write for a new audience? Were there any differences in your process between writing for a younger age group versus teen readers?

I have always loved middle grade. I read a lot of it, especially when I’m writing my YA books, since I find it tough to write the same thing I’m reading. And I always thought that someday I would write for younger readers, but I never found the right story. So, I was focusing on my teen books—and then one day, the idea just popped into my head. I so loved writing for this age group, but it was definitely a challenge to move out of the YA brain and into the head of a younger character. My editor, Justin Chanda, was super helpful. He edits the whole age range—from picture books through YA—so he helped steer me through it. My teen characters spend a lot of time in their heads, and a lot of time reminiscing, and I really had to change my writing style to be more immediate—more experiencing things in the moment, less thinking about what happened last week or last year. And by the end, it had become like second nature.

There’s an undercurrent of grief and loss in this lighthearted summer tale—Ryanna never got to know her mother, and her father and grandparents are still mourning her death. How did you balance the elements of grief and joy?

One thing that I always like to explore in my books is that things don’t happen when it would be convenient. All of life is always happening all at once—the good and the bad, mixed together. And so I liked the idea of a fun summer book, in which we’re also dealing with grief and family rifts. And especially since Ryanna is spending the summer in the place where her mom used to live—the memory of her would be around in a palpable way.

Are there any autobiographical aspects in the book? Camp Van Camp is in the Pocono Mountains. Do you have a connection to that area?

There definitely are autobiographical aspects to it! I grew up spending every summer in the Pocono Mountains, in a place called Lake Naomi. It was amazing—I had a ton of freedom there as a kid and I have such wonderful memories of it. My second YA novel, Second Chance Summer, was set in a fictional version of this town that I called Lake Phoenix. When I thought about a book for younger readers, I knew I wanted to set it in the same place. I wanted my characters to have the same magical woodsy summer atmosphere. And, tragically, my brother’s wife died when my niece was three. So the idea of a single dad and daughter duo—and how that loss might continue to change and impact them both, as well as members of their extended families—was also very much on my mind as I started to craft this story.

One of the pleasures of the book is the jolly, hectic family atmosphere. How did you create the distinct characters and voices? Did your background in theater come into play?

Writing the family scenes was one of my favorite parts of the book! I’ve always loved reading about—and writing—big, chaotic, fun families. It definitely took some trial and error. There were originally three additional cousins—which now seems bonkers, since there are a lot of cousins as is. One fell off pretty early, but the first draft still had a pair of three-year-old twins. I feel like I just spent so much time talking about where they were and who was watching them, that they got cut in draft two.

I definitely planned out the family before I started writing. Honestly, the hardest thing was the ages—keeping everyone straight in the family tree. I named the first four aunts and uncles alphabetically, just to help me remember who was supposed to be the oldest.

It’s funny you mention theater! Both my editor and I have theater backgrounds and I feel like it helps me so much. When you’re doing theater, a lot of the time you have to write out detailed character backstories—most of which never make it onto the stage, but you have to know it. And so I do the same thing when I write novels. I spend a lot of time thinking about these people, building out their backstories and pasts and memories, so that then I can refer to something in passing that happened years before. Hopefully it helps it to feel more lived-in. That was definitely necessary for writing a family that Ryanna gets dropped into—I wanted them to feel established and real—and hopefully, a lot of fun.

What’s next for you?

Next out is my new YA novel, coming in 2024! And I have a second middle grade I’m drafting now that should be out in 2025. It’s another summer story, another group of kids, another mystery of sorts. But a totally different setting, all new characters. I don’t want to say too much about it in case everything changes in the second draft!

The Firefly Summer by Morgan Matson. Simon & Schuster, $18.99 May 2 ISBN 978-1-5344-9335-3