That's what agent Barbara Zitwer ran across on a recent vacation in China. Talking to an old friend, Edmund Cheung in Hong Kong, she learned about 19-year-old Chun Sue, whose China Doll, a dashing novel about her own rock-'n'-roll generation in Beijing, had sold a remarkable 100,000 copies within two weeks of its publication in May. The book was sold out everywhere she went, but eventually she and Cheung came upon two copies in Shanghai (which turned out to have been pirated) and, after a lot of detective work, tracked down the young author and her legitimate publisher, Shen Hoa Bo, in the Chinese capital. Zitwer promptly signed up world rights, had Dutch rights preempted via subagent Mary Ann Thompson and, two days after her return to the U.S., sold it to Julie Grau at Riverhead. There's been a lot of buzz about it in Europe, and Zitwer expects her co-agents there to make hay with it at the Frankfurt fair.