Callistov is a planet currently under Quarantine. It has been under quaratine since the neighboring Dosairian Government unleashed a biological weapon named The Plague or the Chimera Virus. The Chimera Virus is a biological infection aqcuired when one comes in contact with an infected being. The infected beings lose all mentally stability and revert to primal urges. They also have to urge to spread the virus, by biting others who are unaffected.
Currently there are survivors of the Chimera Virus on Callistov, but few are capable of leaving the planet. They refer to themselves often as Crusaders against the Plague. While people offworld refer to them as The Forsaken.