The Stolen Masterpiece: A Nancy Keene Mystery

Join precocious teenage sleuth, Nancy Keene, on another of her international adventures. This book finds her in Amsterdam visiting her newly-found Dutch relatives who have recently discovered a secret room in their house that contains valuable artwork, including a Vermeer masterpiece worth millions. Someone has stolen it, and it’s up to Nancy and her team to find out who. If you enjoy travelogues, this book includes descriptions of some of the writer's favorite sights in Holland.

Here is a great reader review for this book on Goodreads:
"The Stolen Masterpiece is book #5 of the Nancy Keene mystery series, a parody of Nancy Drew. It was by far my favorite story and most like Nancy Drew.
Nancy has delved into ancestry.com, after finding letters written by her great grandfather to family in Amsterdam and has discovered family living there: Dominique and his family- parents Hans and Veronique and sister Nortje. This is her mother’s family. When Mr. Keene has to travel to Amsterdam on business Nancy, Beth, and Hannah, who are on spring break, accompany him. We are treated to some history and descriptions of scenery. Nancy also knows quite a bit about famous paintings, especially by Vermeer and Van Gogh. At the art museum they meet Sophie, the curator, who seems interested in Mr. Keene. Nancy promotes the attraction between the two until they become mutually interested and then seems jealous.
Dominique, a cute guy her age, shows Nancy into a secret room they recently found that is full of old paintings. They have deduced that the Jewish people who lived in their house in the World War II era hid them away before being taken off to concentration camp. His family has tried to trace the family but they were all killed in the war. Nancy is sure that one of them is an unsigned Vermeer. Before they can do anything about it, the house is broken into and the painting stolen! Who knew about the secret room? The carpenters who fixed it when a wall was ruined with water? One guy at school who Dominique told? The kids set up a “sting” to trap the thief but before they execute it Nancy figures out who the thief is and recovers the painting. I don’t think the thief was ever punished. The Vermeer is donated to an art museum; the other paintings that are also worth much money will be sold and Hans and his family will make many euros.
At the book’s end Nancy and her chums appear on a TV show to promote genealogy."