The Orc Tribe

Granak was an orc with ambition. As a young man he went to Aron's Bowl to train as warrior. As an orc, he was met with distrust and revulsion, until he explained he was a half-orc, looking for his father. Then he was looked on with mild distrust and mild revulsion. He signed on with the town guard, and was put to work in the forge with the a one-legged dwarf named Gnarls. After three years learning to make swords and armor, he became disillusioned with the hope of ever being taken seriously as a soldier.
So, he went back to his tribe. Unfortunately, they cast him out as tainted with humanity. Adopting the surname Smith, he struck out on his own to ply his trade as an adventurer. Finally, he found a circle he could move through and be accepted on the basis of his intellect and ability. He continued in this vein for a number of years, accumulating a healthy stash of weapons and gold that he squirreled away in a private hideout he set up in an old abandoned mine.
Eventually, he grew disillusioned with the life of the adventurer, the prejudices against orcs in society, and the pretense he had to maintain to be accepted. Wondering where to go next in life, the party he was with got captured by orcs and taken prisoner. Recognizing one of the captors as a rousing, he was able to get released, and accepted into the tribe.
After a few more years, he sickened of the petty lifestyle of the orcs, and took off with 7 or 8 like-minded individuals. They set themselves up in his abandoned mine and started their own tribe. Combining a mix of adventuring panache with the brutal savagery of a tribal lifestyle, they started their mining enterprise, after a few months of raiding mining transports. They raided a small mine within 3 miles of their own, and killed the leaders, keeping several miners alive to continue running the mine.
Now, they've set their sights higher, going after the gnomes. Unfortunately, Granak Smith overestimated the abilities of his subordinates, and the plan faltered. His watchers know the PCs have thwarted his attempt, and he will target them. His first thought is to capture them and bring them to the working mine for interrogation.
Granak wisely kept his treasure and store of gear secret, even while basing his operation from his hideout. With the mine under his tribe's control, they have moved their lair into the working mine. Granak likes to spend time on his own in his own sanctuary. He doesn't allow visitors there generally, and has set up a number of traps to protect the entrance.