Hidden Tunnel

Hidden Tunnel is a single-player instance part of story quest The Mystery Deepens in Tenebrous Mines.

Hidden Tunnel is located in Halls of Utterdark in Tenebrous Mines. Easiest way to find it is to go to federation camp Utterdark Outpost (other camps have teleport masters to go there). From the camp there's direct route to instance entrance.

Read map carefully. Map has two levels on top of each other. Room where teleporter is is directly north of the camp, but you have to take left turn to get there.

Face the mysterious enemy Black Hood here.