Moxie Fleece is in trouble--she is given two weeks to find the missing art of the Gardner Museum in Boston, or else gangsters who think she has some of it will come for her and her family. To solve the mystery, Moxie will have to have the help of Ollie, her best friend; Gramps, her memory-challenged grandpa; and a geometry proof she has set up to help her solve real-life mysteries.