Dragonsbane -- a terrific fantasy novel that gives a whole new twist on dragons and the hunting of them.
Is this Barbara Hambly? Dragonsbane is one of my favourite BH novels. She's been on my must-read list ever since I discovered her Darwath trilogy back in the '80s. I love the Ladies of Mandrigyn as well.
Her HF is not to be sneezed at either. Search the Seven Hills aka the Quirinal Affair is set in ancient Rome and is a story about early Christianity - excellent - and the Benjamin January mystery series set in 19th century New Orleans are also very good.