"Children's books are the best way to share what we want with children," Birdsall says
Author Jeanne Birdsall didn't know what direction to go in after she ended her beloved Penderwicks book series.
Following the adventures of a quartet of sisters, the middle grade novels have been adored by young readers everywhere since Birdsall first debuted with The Penderwicks in 2005. The series' first installment won the National Book Award for Young People's Literature that year, and four more books followed, before Birdsall concluded with The Penderwicks at Last in 2018.
"At the end of it, I thought I pretty much spent myself -- that I wasn't going to be able to do anything as good as that," Birdsall tells PEOPLE. "[That] is actually a really good place to start a new book because I just could have fun with it."
Birdsall's latest novel, The Library of Unruly Treasures, follows Gwen MacKinnon, another memorable young protagonist. When Gwen is sent to stay with her Uncle Matthew for the summer, her time away from home becomes anything but ordinary when she discovers a clan of winged creatures known as Lahdukan living in the local library.
"A good friend of mine has a son who was very small at the time, maybe 4 or 5, who asked my friend why boy fairies don't wear skirts," Birdsall recalls of the novel's inspiration. "What a great question ... it was so very much that kid's way of looking at the world."
Birdsall couldn't get the image of a kilt-clad winged creature out of her mind, and saw it as the perfect opportunity to write a novel about magical beings visible only to children.
"This is [the] first time I had to write a book with fantastical elements that had to really work with people," Birdsall says. "As a child, I always had that sense that if you just looked in the right place, you'd figure out how to get into a different world or how to see different creatures. That's what I'm really interested in, that children do believe that."
Birdsall's other interests -- notably the author Robert Louis Stevenson -- took her to Scotland to research parts of the novel. The Treasure Island writer is just one author mentioned in Unruly Treasures, in which, as its title suggests, libraries play a large role.
"I think one of the points of being a children's book writer is to transfer that love of books over to children," says Birdsall, whose own favorite childhood authors include C.S. Lewis and Noel Streatfeild. "Saying, 'This is a conversation with different writers from the past, and you can be part of that conversation.' That's a very important thing to give to children."
Though Birdsall is now a celebrated name within children's literature, she didn't originally set out to become an author. She spent the early part of her career working as a photographer, and only began writing in her forties, when her husband encouraged her to follow her dream of creating a kids book.
"Children's books are the best way to share what we want with children," Birdsall says. "The best way to reach the number of children is to write a fun book that will show them what you care about and maybe translate into their lives a little bit."
As such, The Library of Unruly Treasures and its summertime nostalgia might feel familiar to longtime readers of Birdsall. The novel was a big undertaking, though the author notes that was for the best.
"There was a huge amount of pressure because I just keep wanting to get better," Birdsall says. "I did that through the Penderwicks. I wanted my writing to just keep getting better and I'm embarrassed by a lot of what I see as writing weaknesses in the first book. I just want to keep setting challenges for myself."
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"I'll just write what I want, which gave me this chance to fall into this amazing world that I created," she continues. "So far people like it, and so it seems as though I met the challenge. That feels really good."
The Library of Unruly Treasures is now available via Knopf Books for Young Readers, wherever books are sold.