"Dragonshadow" by Barbara Hambly

A great character driven fantasy continues

John Aversin, Thane of the beleaguered abandoned backwater Alyn Hold, and his lady, dragon wizard Jenny Waynest, returned from their adventures in "Dragonsbane" to live happily ever after, or so both readers and characters hoped. But life has no happy endings, especially in the harsh Winterlands. Aversin has spent his whole life protecting the people of this land. He risked his life for his king and brought back books and soldiers from the southern capital. Now the newly filled garrisons are under seige by a huge bandit army, an army with a mage. And if that wasn't enough another dragon has appeared - even if it doesn't kill his people, they'll starve to death if he doesn't stop it's predations on their flocks.

And things are going to get even worse. After a thousands years of (relative) peace, demons have found a way back to the land of men. They're coming after mages... starting with John and Jenny's young mageborn son!

See the review for "Dragonsbane" for the review - it's the same for the entire Winterlands series.

Be sure to start read the books in order:
1. Dragonsbane (ISBN: 9780345349392)
2. Dragonshadow (ISBN: 9780345421883)
3. Knight of the Demon Queen (ISBN: 9780345421906)
4. Dragonstar (ISBN: 9780345441713)