Unfortunately, this one was not as good as I'd hoped. The idea of a "witch for hire" who fights monsters sounding pretty exciting (at least to me!), but I felt like I was dumped into the middle of the story and was missing out on an awful lot.
Thessaly, last of the powerful Thessalian witches, has spend the last two years fighting monsters then moving on when her neighbors begin to become suspicious. When Fletch, a lovable "ghost" comprised of all the people Thessaly has ever killed, arrives, Thessaly discovers he has, out of loving concern for her, made her part of a monster-killing contract without her knowledge, hoping to add some fun and adventure to her life. Thessaly is understandably furious, but has little time to be angry when she discovers Fletch's latest contract has transferred the wrath of a Tharmic-Null to her, his beloved; it's the one thing Thessaly can't kill.
Thessaly made her first appearance in Neil Gaiman's The Sandman and she's certainly deserving of her own book. However, this one doesn't do her justice. The artwork is great, but the story lacks development.

Willingham, Bill and Shawn McManus. Thessaly: Witch For Hire. New York: DC Comics, 2005.