The Insiders campaign (aka the Sigil Campaign) starts with a group of level 5 player characters who are natives of the extra-planar city of Sigil (aka The Cage or City of Doors). These PC’s are about to join an elite guild called the Insiders, an organization that dates back to some time before the Gith broke free of their Mind Flayer slavers and became the two different races they are today.. so, quite a long time ago. The Insiders are a mysterious bunch, but they have a highly respected reputation for being able to get into tricky places, do what they are payed to do, and get out again without the deed leading back to the paying client. They also have a reputation for having more information on planar travel and the portals of Sigil than most other mercenary guilds who are not specialists in information brokering. The members of the guild are identified by the highwayman great cloak they wear, and a device each of them carries, known as an Astron, which they are said to use when navigating the planes.
As prospective members of the guild, the player characters must first complete three tasks, and then begin their career as Insiders.. a career which reaps many rewards, but also entails constant activity to pay their guild dues and maintain their own, and the guild’s excellent reputation.