You are a member of the family known as the Thumbs, a crime syndicate that extends its reach throughout all of known civilization. Fearful citizens even claim it reaches into the Beyond, the foul claws of its demon-lord Thuu’rzet extending past the boundaries of the material plane.
Drawing its name from the placement of the iconic invisible ring its members wear, the Thumbs are bound by oaths of secrecy and fraternity, its members compelled never to speak of its meetings, and forced to stay their blade against their compatriots. They carry out deeds in the darkened streets, crowded noble dance halls, and dank dungeons of the world, gathering wealth and power for their own means.

Membership in the organization is by invitation only. One is either sponsored in by an existing member or called to service by Thuu’rzet himself.
Sponsored members can climb the ranks, taking jobs from petty thievery to sustain the guild all the way up to deep-plant government infiltration, dungeon-crawling field missions to recover artifacts of power, and transcontinental travel to sow the seeds of discontent across the seas.
It is Thuu’rzet’s chosen Warlocks that make up a special class, called upon from the lowest of the low, the cruelest of the cruel, the greediest of the greedy, to do the deeds which even ‘regular’ thumbs deem too dirty. Compelled by their pact, they carry out the deeds of their master with ruthless efficiency.

The punishment for betrayal in the Thumbs and for being caught by the law is the same: removal of the left thumb. When cut off, the ring unbinds from its wearer and clatters visibly to the ground, for all who bear witness to see its shame. The wound is then sewn shut and cauterized in an unmistakable way, to mark the fools who dared cross the organization permanently.
Thumbless members of society are considered worse off than the dead.