From the publisher's website:
Something wicked this way comes!
As written, Leagues of Adventure is a game of adventure and exploration, full of heroes with stiff upper lips and a desire to push the boundaries of knowledge. Yet the Victorian Age also sees the birth of true Gothic Horror. This supplement expands the setting far beyond the realm of the rational and into the realms of mentalism, the occult, and magic.
Designed for players and GMs alike, this supplement provides advice on running Gothic Horror games; new Archetypes, Skills, Talents, Flaws, and Leagues suitable for the genre; corruption and fortune-telling; magic and mentalism; occult tomes; a bestiary crammed full of monsters; adventure seeds; and sample characters and lackeys.