The author of Graceling (Harcourt) is nothing like her heroine, Katsa, whose mixed eye color (one is blue and the other green) signifies in her particular world that she is “graced,” born with a unique skill. Katsa's grace is for killing.

Cashore, one of four daughters of a religion professor at Kings College, a small Catholic school in Wilkes-Barre, Pa., has quieter talents. Though it took her a while to figure out precisely what she wanted to do, she's known since childhood that it ought to have something to do with books.

“We would go to the library and the number of books you were allowed to take home equaled your age. That way we could make sure we got the right number of books back,” said Cashore, now 32 and living in Jacksonville with a younger sister. “But that meant, when I was 12, I was reading 12 books every two weeks—Judy Blume, Beverly Cleary, Katherine Paterson, Madeleine L'Engle, then on to 19th-century British literature.”

Her undergraduate degree from Williams College was, naturally, in English literature, and she went on to Simmons College for a master's in children's literature, thinking she might become a librarian. A creative writing course, during which she completed a contemporary, realistic middle-grade novel (which “still needs a lot of work,” says Cashore) kickstarted her desire to write. After graduation, she supported herself by freelancing, mostly writing elementary-level educational material.

Novel #2 was Graceling. The characters—Katsa, the gold- and silver-eyed Po, Prince Raffin—arrived before the story did. “Right away I knew they weren't regular human beings and that they lived in some sort of vaguely medieval, pre-Industrial Revolution, pre-feminism world,” Cashore said. “But the plot did not come naturally. The plot had to fit all the different ideas I had about the characters.”

A first draft took a year and a half. A college friend knew agent Faye Bender. But Bender's Web site said: “No fantasy.” Cashore queried to see if she would make an exception, and was given permission to send 50 pages. “Then I got a call from Faye saying she wanted to work with me. She was the only agent I contacted and a few weeks later we had an offer. I had 10 years of fight in me and suddenly nothing to fight!”

The offer came from Harcourt editor Kathy Dawson, who had never acquired a fantasy before taking on Graceling. “I didn't read [the manuscript] for a long time because it was so long and because it was fantasy,” Dawson recalled, “so I finally got the polite nudge [from Bender]. “I took it home and that night I called her to say 'I'm 50 pages in and I'm really loving it.' Katsa—violent, conflicted, independent Katsa—she was the best character I'd met in a manuscript in a long time.”

Graceling has been out for two months and Harcourt has gone back to press twice already, with 110,000 copies in print. Rights have been sold in 12 languages.

Cashore has also finished a prequel, Fire, due out next October; she is now working on a third volume, centered on Bitterblue, another character from Graceling.

Cashore's eyes are blue, by the way. Both of them.