The Curse of the Phantom Pirate - Fergal O'Brien, #3

Having finally become a wealthy man Fergal O'Brien no longer has to sell his universal remedy to cure all ills, but that leaves him with the problem of what he wants to do instead. An opportunity arises when he comes across a theater that has been abandoned after the untimely death of its owner Harold Beaumont. Fergal sets out to bring his skills as a showman to a larger audience, but he soon faces plenty of problems.
The theater has a poor reputation, it's haunted by the ghost of a pirate and, worst of all, the gunslinger Laramie Todd wants a regular pay-off or he'll burn the place to the ground. As the theater has never made a profit, to succeed in his new venture Fergal must work out how Harold ever managed to pay Laramie in the first place, a mystery that can only be solved by confronting the curse of a long-buried pirate.