Mandie and the Buried Stranger

is the thirty-first book in the Mandie series.
==Book Description==
It's spring break, and Mandie is eager to visit the Woodards, especially her friend Joe. Almost as soon as they reunite, they discover a large pile of mica in an unexpected place. It's an even bigger mystery when the entire mound disappears the next day. Who would have done such a thing, and why?
(Description from Amazon.com)