Humans have been visiting the Dorgeshuun mines for some time now, but no Dorgeshuun has visited the surface since the signing of the Lumbridge-Dorgeshuun treaty. The Dorgeshuun Council fears that the H.A.M group may be planning another attack, and want to send an agent to the surface to investigate. But they do not want to send someone to the surface without a guide...
Wander around the south of the stage, Zanik will spot a trapdoor.
Pick the trapdoor and go down. You'll need Zanik to kill the guards in this room to continue:
Walk past the first guard and talk to him; Zanik will shoot him.
Squeeze through the hole in the wall to get into the south-west room. Wait for the guard in the central corridor to walk by, then squeeze through the northern hole in the wall. Run west behind the stationary guard and talk to him. Zanik will shoot him.
A guard is patrolling the central corridor. Say, "Now," when his back is turned. Zanik will snipe him.
Move to the other end of the central corridor, and talk to Zanik again. Tell her to wait. Then, run out and south down the room making the north-east guard follow you. Zanik will shoot him as he passes the central corridor again.
For the final guard, go to the end of either the left or right passages, and talk to Zanik again, tell her to wait there; then, go to the other passage, and distract the guard whilst Zanik shoots him.
Listen at the door. After Zanik hears a bit of info, a senior guard will respawn and arrest you.
You find yourself in the jail. Talk to Jimmy the Chisel. He will tell you that Sigmund took Zanik outside.
Pick the lock to escape, go back outside, and you'll find Zanik dead. Take her body.