From the Chaosium website:
A sourcebook for Cthulhu Rising – Call of Cthulhu roleplaying in the 23rd century
By the late 23rd century, the gas giant Jupiter and its sprawling system of rings and moons is home to a colonial population of millions.
Over the century and a half since the colonisation of the outer planets began in earnest, an aggregation of settlements and outposts have developed to mine the raw materials which drive the economy upon which the United Earth Federation depends. The types of settlements found in the region are varied, ranging from the subterranean conurbations at the top of Europa’s oceans to the harsh mining towns of Io; from the Callisto orbitals to the countless corporate research outposts.
Despite its location in the most densely populated and heavily-policed star system in the United Earth Federation, Circum-Jove remains a fertile breeding ground for a multitude of subcultures, outlaws and weird religious cults. It’s also a hotbed of new technologies research and home to corporate infi ghting at its worst.
Humanity is not the first star-faring culture to have visited this region. There are beings far older than Man. Ancient, malign beings that would be described in human terms as pure evil, but for whom such a label is meaningless. Here, they wait. Beneath aeons old ice and rock. In the dark spaces between the stars. Waiting for when the time is right.
Some nightmares are very real. Jovian Nightmares.
Contents:
Introduction
About Jovian Nightmares
About Cthulhu Rising
Acknowledgements
Dying in a Winter Wonderland
Circum-Jove: History
Jupiter
Io
Europa
Ganymede
Callisto
Other Locations
Organisations
Jovian Investigations
Jovian Secrets
Cut Back Blues
Escape Velocity
Adventure Seeds
Glossary