Which Mary Stewart book will I read next?

Really cool quiz from Jennie and Julie's Mary Stewart blog:

Which Mary Stewart novel should you read? Your Result: Airs Above the Ground   Lovely Vanessa March did not think it was strange for her husband to take a business trip to Stockholm. What was strange was the silence that followed. Then she caught a glimpse of him in a newsreel shot of a crowd near a mysterious circus fire in Vienna and knew it was more than strange. It was downright sinister.
Touch Not the Cat
Nine Coaches Waiting
This Rough Magic
Wildfire at Midnight
The Ivy Tree
Madam, Will You Talk?
My Brother Michael
Which Mary Stewart novel should you read? Make Your Own Quiz

I haven't read that one yet, so it will definitely be my next!