Vicious Circle by Mike Carey

Felix Castor has reluctantly returned to exorcism after the case of the Bonnington Archive ghost convinced him that he really can do some good with his abilities ("good," of course, being a relative term when dealing with the undead).

But his friend, Rafi, is still possessed; the succubus Ajulutsikael (Juliet to her friends) still technically has a contract on him; and he's still dirt poor. Doing some consulting for the local constabulary helps pay the bills, but Castor needs a big, private job to really fill the hole in his overdraft.

That's what he needs. What he gets - good fortune and Castor not being on speaking terms - is a seemingly insignificant "missing ghost" case that inexorably drags him and his loved ones into the middle of a horrific plot to raise one of Hell's fiercest demons. When Satanists, sacrifice farms, stolen spirits, and possessed churches all appear on the same police report, the name of Felix Castor can't be too far behind.