The Mystery of the Manse was an ongoing story in six parts, revealed in the first six issues of SLG's Haunted Mansion comics. Written by Dan Vado, it details the supposed history of Gracey Manor and its infamous owner, William Gracey, revealing how the mansion became haunted in the first place and later a home for 999 wayward souls.
Each part is opened with narration by Gracey himself, who is portrayed as the body hanging in the rafters above the Stretching Room, as he relates the grisly history of the mansion.
Illustrated by Mike Moss and Brian Belew
William Gracey is first mate aboard the Pomona, a trading ship in the Caribbean that gets caught in a terrible storm while making a run to Barbados. The captain, Randall Pace, stubbornly orders his crew to take the vessel through the squall despite the crew's protests, claiming their secret cargo is too important to arrive late. When Gracey descends to the hold to look for a sword to cut away some tangled rigging, his curiosity gets the better of him and he discovers that the cargo is actually firearms: Pace had become a gunrunner without consulting his crew. Gracey confronts Pace and demands the truth about the cargo, for putting the crew's lives at risk without offering extra compensation, but Pace refuses to give a straight answer.
A bolt of lightning then strikes the mast, causing a mass of rope and canvas to fall on Pace and entangle him. He yells for Gracey to cut him free, and Gracey obliges by decapitating Pace with a sword in his rage. Gracey would place Pace's head in a hatbox in anticipation of a burial in Barbados, but then decides he himself might take advantage of the cargo. Thus, he becomes the pirate Captain Blood.
Illustrated by David Hedgecock
William Gracey, now Captain Blood, starts his infamous career as a gunrunner and smuggler, turning to piracy only when the merchants he traded with started refusing to deal with him - it seemed Captain Blood always got the best end of the bargain through subtle manipulation and negotiation. Blood discovers that being a pirate is much more lucrative, and becomes a notorious marauder with a mountain of riches and a growing number of enemies. He laments that perhaps he has started too late, as the Golden Age of Piracy has long since passed. And as the French begin closing in on him, he realizes that there's no way he can survive much longer.
Taking back his old name, Gracey betrays his crew to a French garrison, disguising himself a simple shiphand from the Pomona and revealing its location in exchange for clemency. He then arranges for his ship to make anchor in the planned spot and escapes under the cover of darkness with much of the plunder he's acquired. The crew is easily slaughtered by the French navy, and the Pomona is set ablaze.
In exchange for the information, Gracey is sent to New Orleans with his secret stash of pirate loot, planning to start fresh now that there is no one alive to accuse him of being Captain Blood.
Illustrated by Mike Moss
Gracey arrives at Laffite's Landing in New Orleans, posing as a traveling businessman and looking to establish himself in the city. It is revealed that, as Captain Blood, Gracey had encountered Jean Lafitte on a number of occasions, and had knew the old pirate had former acquaintances still lurking in the city. He contacts an attorney and former crewmember named Brian Belew to help him find a home, and Belew takes him to an abandoned antebellum mansion just outside the city.
The manor, though still new, had apparently been deserted not long after its completion - even its architects had vanished without a trace as soon as the building was finished. Local legend claims the land is cursed - a good excuse to keep the nosy away - but Gracey is not a superstitious man and enters the house, though he soon becomes disoriented and lost as peculiar phenomena begin to occur; starting subtly, the hauntings quickly escalate as Gracey wanders into the Endless Hallway, encounters a specter in a coffin, and notices a floating candelabra and breathing doors.
Unable to be a skeptic any longer, Gracey suddenly laughs like a madman: he's found an ideal home to hide away in.
Illustrated by Mike Moss
Gracey has managed to settle into his life in the mansion, despite the presence of the unquiet dead. He feels it is a means to a end, a way to keep his secrets and himself safe and secure. He is content with his solitary life until he crosses paths with Emily de Claire and falls in love with her, seeing redemption in her. They court, and soon they are set to be wed. However, Gracey knows he cannot bring Emily to live in a haunted mansion.
One day, Madame Leota appears on Gracey's doorstep and offers her services in dispelling the dead. She similarly is smitten with Gracey and attempts to seduce him, but Gracey rebuffs her advances and orders her to do her job. Scorned and bitter, Leota nevertheless carries out her task, and in contacting spirits from the other side discovers that the anguished spirits of Gracey's former crewmen seek to torment him, learning the truth about his past as a pirate. Leota hatches a plan to invite the vengeful dead in rather than banish them, and lies to Gracey, telling him she's done her job and cleansed the house of phantoms.
Overjoyed, Gracey prepares for his wedding. Unbeknownst to him, however, something sinister stirs in the attic...
Illustrated by Mike Moss
The day of Gracey's wedding arrives, and guests begin to pour in as preparations are made. Though uninvited, Leota slips into the house and prepares to set her revenge in motion; meanwhile, Emily goes on the traditional hunt for the things a bride-to-be must have on her wedding day: something old, something new, something borrowed, and something blue. Emily ascends to the attic in search of something old, and among the bric-a-brac she spot a hatbox. Before she can open it, a ghastly voice interrupts her and a headless figure emerges from the shadows. Taking his head from the hatbox, the ghost is revealed to be Randall Pace, and he recounts his murder and the truth of Gracey's dark past to Emily. Several other ghosts, Gracey's former crew, appear as well, and tell of their own deaths. Emily panics.
Hearing Emily scream, Gracey races to the attic, only to find his bride died of a broken heart, Pace's ghost looming over her. He mocks Gracey as the rest of the spirits drive away the wedding guests, saying how Emily couldn't handle the truth of Gracey's past. As he (presumably) departs for the afterlife, Pace tells Gracey to thank Leota for the invitation.
Filled with rage, Gracey finds Leota in the midst of an incantation and strangles her to death. With his life effectively destroyed and blood once again on his hands, Gracey resigns himself to the end. He enters the mansion's cupola and hangs himself from the rafters.
Illustrated by Mike Moss
Wrapping things up, Gracey's ghost explains what happened as a result of his actions: when Leota died in the midst of her seance, the violence of her demise resonated psychically across the world, and like a Siren's call began to tug at wayward souls. Leota continued her seance, even in death - not realizing she had died - and the mansion became a beacon for specters and ghouls. Initially, the first ghosts to arrive were from the local graveyard, but soon far-flung phantoms from all corners of the globe began to turn up at Gracey Manor, looking for a place to spend their afterlives.
Occasionally, mortals would show up, either pulled there by Leota's call or looking for hidden treasure. Though most flee in terror, one woman named Mary is bold enough to stay in the house and, upon finding Gracey's corpse hanging in the rafters, sets out to find the pirate gold he had hidden. She succeeds in this, but keeps it in the mansion so the ghosts might protect it, and leaves Gracey's corpse up as a warning to trespassers. Yet she similarly keeps the house in order, like a maid, and soon hires other young women to help her in this and be her successors. When she dies, she leaves her fortune behind to another young woman who will carry on the tradition, and her spirit joins the other happy haunts in the mansion.
Gracey is able to leave his decaying body and wander the house as a wispy, invisible spirit, but refuses to enter the attic, so as not to disturb Emily's rest. In the end, it is revealed that he has told his whole story to a treasure hunter, and challenges the interloper to find his way out now that he "knows too much."
- It should be noted that there is no proof at all that this backstory is canon, even to the comics themselves; knowing the Ghost Host's usual playful nature, it is perfectly possible that he actually invented the whole thing, or at least twisted certain facts, for the purpose of confusing the mortal treasure-hunter.