I'm re-reading this wonderful mystery series from the 1980s. This is the official first book in the series, but there is actually one that Doris appears in prior to this story called "Dr Doom Superstar".
This book sets the scene for the series. Doris is 18, Jewish, overweight, and is all about women's rights. She lives in southern California. As a H.S. graduation gift her parents send her to New York City alone to stay with her Aunt and Uncle there. Uncle Claude is the Diplomat from the African nation of Dakama. When Doris arrives she's met at the door by a man without a beard who says he is Uncle Claude but she's not sure- Uncle Claude has a beard. He tells her that they were called home to Dakama and that she must stay in a hotel. A suspicious note purported to be from her aunt sends Doris to the police department to report that they have been kidnapped. She is not taken seriously but does meet Carl Suzuki, a young policeman, who tries to help her. Then there is an uprising in Dakama. They get themselves embroiled in a big international mess before it's all sorted out.
Check this series out if you have never read it.