Ransom Riggs and Tahereh Mafi spend their days in Santa Monica, sitting side by side at a shared desk in identical chairs in their backyard office, wearing headphones, working at their laptops. Across a cool green expanse sits their Spanish-style house, hidden behind a vine-covered wall.

“I really loved books about secret worlds, like ‘The Secret Garden’ and the ‘Bridge to Terabithia,’” says Riggs, whose young adult novel “Miss Peregrine’s Home for Peculiar Children” was a bestseller in 2011. “Stories that were grounded in our world, but there was a way to get to another world. I tried to recall that when I wrote ‘Miss Peregrine.’ I like finding the portal.”

In “Miss Peregrine’s Home for Peculiar Children,” Riggs created a story about children with extraordinary if not always useful powers (floating, summoning bees), building it around vintage photographs he’d collected.

The sequel, “Hollow City” (Quirk, $29.95), came out Tuesday; three weeks later, Mafi ― the couple married in a small ceremony in September ― publishes her latest, “Ignite Me” (Harper, $17.99). The book concludes her “Shatter Me” trilogy, also bestselling, also for young adults. Theirs is a two-bestseller household.

Mafi’s series is a dystopian teen romance, centered on a character who has been imprisoned for her powers and may be losing her mind. It begins with chaotic text that includes strikethroughs and repetitions, then evens out as she finds herself.

“I wondered whether or not what I was trying to do resonated with anyone. Did they get it? Did they understand that she’s a girl who lost her voice, lost her identity?” Mafi explains. In December, she got an answer. For the Guadalajara International Book Fair, more than 10,000 teens read her book and submitted letters to share with her during a live event.

“They had written their letters in a similar vein as the book,” she explains. “And they talked about feeling that same kind of isolation, going through that same kind of difficulty, in a way that was just so powerful for me that I couldn’t control my own emotions. I was like, wow.” On stage, she started to cry.

“It was so nice to know that someone really got it,” she says. “I think in life you just need one person to understand you. Like, you know, when you get married.” She looks over to Riggs.

Together, Riggs, 34, and Mafi, 26, are on their way to becoming the kind of couple that casually finishes each other’s sentences. Before we start to talk, they warn me they can get too cute ― but, in fact, they’re enchanting.

“She’s working on a new book, and she finally read something aloud to me,” Riggs says, before turning to her directly. “To hear you read it out loud, I’m like, ‘Oh, that’s what you meant.’ Perfect. Even better. You should probably do your own audio books. You have many alternate careers you could be very successful at. Fashion designer. Blogger queen.”

“We’re clearly very biased,” Mafi adds.

“Runway model,” Riggs continues. “See, this is what we were talking about before. Gross-out cuteness.”

Riggs, Mafi says, has changed the way she writes. “He likes to take walks, make himself a cute little coffee, check the mail and play with the cat,” she says. “While he’s writing! I was like, ‘Whoa, that’s interesting.’”

She continues: “Before Ransom came along, I wrote in very obsessive bursts. I’d sort of lock myself up and write until the book was finished. I would eat bits of cold bread and sip my cold tea while I was working. Just the most depressing picture you could possibly paint.”

“Yeah,” Riggs interjects, “so you make me sad. I’m like, ‘I made you dinner.’ You look up at me with big eyes, like ‘Someone’s speaking?’” He brightens. “I’m like, ‘Come to the light.’”

The reference, to the movie “Poltergeist,” comes from Riggs’ long devotion to film. He got a graduate degree at USC’s film school, then wrote screenplays without making much headway.

“Writing novels is so much more fun than writing screenplays,” he says. “I love pictures, I love movies. Authoring a screenplay feels unrewarding, like I only did half the work and then quit. Instead I wrote a book that had photos in it.”

“Hollow City” also has images in it. An adventure set in wartime England, it features photographs Riggs found while visiting collectors across the country. “I brought my flatbed scanner with me and would sit in their living room and be like zz-zzz-zz,” he says.

Meanwhile, “Miss Peregrine” and the “Shatter Me” series have both been optioned. The former is closer to filming, with Tim Burton slated to direct, casting coming soon and a release planned for 2015.

“But still, I’ll believe it when I walk into that theater with my bucket of popcorn and the credits start rolling,” Riggs says. “I’m emotionally arming myself for disappointment ― because it’s Hollywood.”

“It’s his job to expect the worst and my job to be extremely excited,” Mafi observes.

Her energy is a force. After receiving her undergraduate degree at Soka University in Orange County, Calif., she wanted a rest before graduate school. For her, that meant taking a full-time job.

“I was instantly bored,” she admits. “I can’t take time off.” Instead, she wrote five manuscripts in a year ― and then “Shatter Me” found its way to an enthusiastic agent, and eventually to Harper Teen. Fans of the book are avid and outspoken. But Riggs is her first reader.

“I don’t think it would have worked out if we didn’t like each other’s writing,” she says.

“I don’t think so either,” Riggs agrees.

“It would have been really hard,” says Mafi.

“Too exhausting ―” Riggs begins, and Mafi speaks up, “― to lie all the time,” they finish, together.

By Carolyn Kellogg

(Los Angeles Times)

(MCT Information Services)