Guardian Spirits - Spirits, #3

Psychic medium Vincent Night and his lover Henry Strauss have spent months striving to uncover the dark secret harbored by Vincent's dead mentor, James Dunne. Their only clue comes from a journal: Dunne was seeking to restore the Grand Harmonium, an artifact meant to breach the walls between life and death. Fate seems to intervene when Henry and Vincent are offered a job investigating the haunted orphanage where Dunne lived as a youth.
But the ghosts of the orphanage don't rest easily, and the lovers soon find themselves in a battle to locate the Grand Harmonium before it falls into the wrong hands-and unleashes evil upon the world.