The most relevat information is found in Chapter 4: Shadow Stalkers. This details Earth in the year 1872. This is a few decades prior to MoTRD, but most of the contents should still be relevant.
Shadow Stalkers is linked to the Shadow Chasers campaign from the main D20 Modern Sourcebook.
- The Fellowship: An organization of monster slayers, including Shadow Slayers, Occultists, Shamans, Spiritualists, Mesmerists and Frontier Marshalls.
- Baskerville Hounds (Hellhounds)
- Sherlock Holmes
- Doctor Henry Jekkyl
- Hyde: Not just a single individual, but many can now be turned into these creatures.
- Order of the Crimson Dawn: Evil organization, formed 1867, seeking to use Shadow for their own agenda. Crimson, Red, a reference to MotRD?
- Omar al-Habib: Wealthy Scholar from Morocco, interested in archaeology
- Heinrich Schliemann: Archaeologist known for discoveries at Troy.
- The Tomb of Maenthro-Apepi, the Desecrator of Souls, Priest of Apep has recently been discovered in Egypt.
- Troy excavation might have ghosts and animated horses.
- Fallen Birch, a town in California, best known for the Full Aces Saloon. (Map, NPCs and details provided)
- Jim Franklin, a US based Vampire
- Victor Muratz, a poker player
- Willy Spinner, a poker player
- Wyatt Earp
- Art "The Artist" Mortimer, a sherrif
- Thomas Blair: Bartender at Full Aces Saloon
- Buddy: Town Drunk
- "Horse" Feathers: Farmer
- Flippin' Bill McPhil: Gambler
- Ezekiel Pine: Town Chemist
- Sharps: Journalist from San Francisco Chronicle.
- Duncan Washington: Town Assayer
- Martin Cambridge: Town Dentist. Incompetent. Married to Mary Cambridge.
Elliot Klein, Explorer
Art Mortimer, Frontier Marshall
More later. Do you think any of this could become useful in a Masque of Red Death Campaign?