Ministry of Clandestination

The Ministry of Clandestination works to ensure that the shadow trolls remain hidden from the world even though their very intellectual existence demands them witnessing others in the world. Shadow trolls start out as dim-witted as other trolls but have the ability to absorb the memories of another shadow troll they consumed. Over the eons, shadow trolls changed from vile cannibals to a refined and organized civilization based upon the eating of each others fingers that do grow back. Intelligence can only be transferred if a troll witnesses a sentient act, so spying on sentients from the shadows is vital. Fingers are a shadow trolls greatest treasure, and every grown troll has a trove of fingers stored in brine.
As the shadow trolls grew in numbers and intellect, they discovered a way to store memories in clear crystal orbs that those who are not shadow trolls can experience the memory stored into the orb. This invention created a new business venture, that of the secret brokers. Secret brokers are at high risk of being discovered so they are more closely watched by the Ministry of Clandestination. The trading of secrets requires a shadow troll to leave the shadows and physically interact with someone else they are not going to kill. Disguising costumes and magical trinkets are needed for this, yet another business venture.
Any time the truth of a shadow troll is revealed, the agent trolls of the Ministry of Clandestination arrest the exposed troll and take it to the Ministry. The entrance is in the shadow of the bridge to nowhere in the town of Blackstone. Inside the ministry it is imprisoned until it proves it has learned how to be secret. Each troll is allowed two offences. The third offense it a death sentence as that troll will be taken into the Ministry and turned into memory dust.
Memory dust is used on all non-trolls who witnessed the reveal. Those very rare few who are unaffected by it are taken to the Ministry of Clandestination where they spend the rest of their lives serving the ministry or, if they prove difficult, eaten.

We are the Never Known

MEMORY DUST
Memory dust is the dehydrated remains of a shadow troll. A pinch of it is enough to erase the most recent hour of memory. A rare few are immune to the dust. Just as rare, are the few who are exceedingly vulnerable to it. These latter few lose all their personal memories and the true cause of amnesia.