LOS ANGELES - Cornelia Funke builds wild, wondrous worlds with her words, from the back streets of Venice, Italy, to a land of fairies and gargoyles called MirrorWorld. That's where Jacob Reckless, the treasure hunter hero of her latest series for young teens, enlists a dwarf and a vixen to help him undo a fatal curse.

Still, when she contemplated a MirrorWorld app, Funke says she felt a little like Bilbo Baggins accepting an invitation to an adventure. She wasn't sure where the path would take her.

The app (released for iPad on April 17) arrived just a couple of weeks after "Fearless" (Little, Brown), the second in the MirrorWorld series. In the first, "Reckless," Jacob saves his brother from becoming a gargoyle. In "Fearless," Jacob faces a fatal fairy curse - on himself.

Maybe that's why Funke has jumped wholeheartedly into a new way of telling stories she hopes will in turn jump-start the imaginations of her fans and newcomers to her complicated and moody characters: She understands and appreciates the concept of risk.

Funke met Mathew Cullen, co-founder of Mirada, the Marina del Rey, Calif., studio that produced that app, at a party, and they quickly found themselves in creative sync.

"You try to find these synergies in life. You try to find people who like to do things a little differently," says Cullen, who has directed and produced hundreds of commercials and music videos, including Adele's "Chasing Pavements" and Grammy winners for Weezer and Black Eyed Peas.

Together they created the 16 distinctive stories (15 by Funke) for the app, which are told in words and other media, including film, wood-cut-style drawings and fabric art.

There are witches' recipes that call for the leg of "a stout child" and the "sleep crust" from a dozing little one. The swirly, entranced look of a story titled "The Spell of a Fairy" matches the tale of what it's like to fall in love with one. Some stories provide background to the "Reckless" series, but all are meant to stand alone.

The app ($5.99, with one story, "One for the Other," available as a free download from iTunes) uses the Ogre Tavern, filmed in a bar near downtown L.A., as an entry point, and from there, there are about two hours of content.

Originally an illustrator, Funke has sold millions of books for children of all ages, with "The Thief Lord" and the "Inkheart" series perhaps the best known.

The title of "Fearless" is perhaps better worn by Fox, the shape-shifting vixen whom Jacob saved from a trap years ago and who likely will become increasingly important in future books. In human form, she is growing into womanhood, and in "Fearless" she confronts "the fear of loving too much, the fear of looking at her past," Funke says.

Lives are, of course, at stake, and Jacob spends much of the plot searching for a way to break a spell that is killing him.

"It liberates him to think he's dying," Funke says. "It's been great to be a treasure hunter, but now he has to question what he's doing and why he's doing it."

The Reckless books are aimed at kids around 14, Funke says, because of the mature themes and scary plots. There's a child-eating witch and the nearly unbearable pain of fairy curses. But she knows, from fairy tales onward, that children handle frightening stories with remarkable aplomb.

"Children like to be taken seriously. They know the world is dark," she says. "The closed curtain scares us more than opening the curtain and looking at what's behind it."

Distributed by MCT Information Services