Moxie and the Art of Rule Breaking

I've been reading a lot of mysteries and so have my kids. 

This one was great. A lot like the Westing Game, one of my all-time favorite books.

Ages 10 and up. 

From Amazon:

For fans of The Westing Game and From the Mixed-up Files of Mrs. Basil E. Frankweiler comes a clever, treasure-hunt mystery based on a real-life art heist.

Moxie Fleece knows the rules and follows them--that is, until the day she opens her front door to a mysterious stranger. Suddenly Moxie is involved in Boston's biggest unsolved mystery: The Isabella Stewart Gardner Museum art heist. Moxie has two weeks to find the art, otherwise she and the people she loves will be in big-time danger.

Her tools? Her best friend, Ollie, a geocaching addict who loves to find stuff; her Alzheimer's suffering grandfather, Grumps, who knows lots more than he lets on; and a geometry proof that she sets up to sort out the clues.

It's a race against the clock through downtown Boston as Moxie and Ollie break every rule she's ever lived by to find the art and save her family.