Dragon's Tooth by Kristine Kathryn Rusch
Approx. 19,350 words.
Published on July 10, 2010 by
Tara, a former agent of Abracadabra Incorporated, helped shut down black magic all over the world. Now she has retired and runs a little magic shop. On a trip to Paris, she discovers a deadly dragon’s tooth and must shut down the source of its dark magic or risk losing everything.