The Alastair Stone Chronicles28 books in series
Stone and a Hard Place Publisher's Summary
It's hard enough for Alastair Stone to keep his two lives - powerful mage and mundane Occult Studies professor - separate without an old friend asking him to take on a new apprentice. Especially after a university colleague wants him to investigate a massive old house for things that go bump in the night. Still, Stone figures it's an easy job: just turn up, put on a little show, and announce that the house is clean.
Only it isn't. A malevolent spirit is reawakening in the basement, imprisoned between dimensions and intent on escape. If it succeeds, countless people will die. Worse, a trio of dark mages want to help it break free so they can control it for their own sinister purposes. They'll do whatever it takes - including seducing Stone's young apprentice and using him against his master - to get what they're after.
With time running out, Stone has to stay alive long enough to uncover the spirit's secrets. But even if he does, he fears that his own power won't be enough to send it back.