Once upon a time, the entertainment industry was a world that never slept. Magazine editors, models, pop stars, and all the rest visited "vitamin doctors" to get the shots that would allow them to stay up all night and then work all day—in offices decorated with beanbag chairs and Calderesque mobiles. In this world, January Wayne goes from poor-little-rich-girl to grown-up swinger, as she searches New York and Los Angeles for a guy just like Mike Wayne, the glamorous movie producer, who also just happens to be her father.

Though often panned by critics, Susann's slightly sordid yet thoroughly fabulous novel was embraced by her fans. Once Is Not Enough became Susann's third consecutive novel to reach the number one spot on the New York Times best-seller list—the first time any author had accomplished this feat. The novel would be Susann's last great success: The year after its publication, in 1974, the author died of breast cancer.