Cecelia Ahern, daughter of Ireland's prime minister, was in a Dublin boutique last January when her cell phone rang. "I was all twisted about with clothes half on," she says, when the caller—the agent who was peddling her first novel—said, "The deal is for $1 million." Ahern, 22, rushed from the shop, so flustered that "I had to check to see if I was wearing my own clothes."

Used to the spotlight as the second daughter of Bertie Ahern, 52, and his long-estranged wife, Miriam, 49, Ahern (a self-described "solitary" sort who likes to stay at home with boyfriend David Keoghan, 25) is coming to terms with her own fame. Written in three months after she dropped out of grad school, PS, I Love You earned her $500,000 in a movie deal even before the book hit the U.S. this month.

The story of a young woman coping with her husband's death, PS is being marketed as a kind of melancholic Bridget Jones. Ahern, however, is not interested in being a standard-bearer of chick lit. "I didn't know what people were talking about when they said that," she says. "I thought they were talking about Chiclets."