Cover illustrated by Ira Sluyterman van Langeweyde.
Summary
When Mabel's parents leave town without warning, she isn't worried. They're spies, after all. But when her beloved Aunt Gertie is arrested for leading a smuggling ring, then her obnoxious uncle Frank and aunt Stella show up, demanding to be let into the family's private museum, things begin to look fishy. Especially since Mabel hasn't heard from her parents in days. Tackling a mystery like this one is what she has been training for her whole life. Using her self-authored spy rules, will Mabel be able to find her parents and unmask the real criminal before she loses all trust?--Provided by Publisher.
