Daniel Knox is an agent with the CIA.
Well, he is a CIA analyst. Not quite the same thing as a field agent. Vitally important to the mission because without intelligent people analyzing data from all sorts of sources and making logical conclusions, the field agent can often be barking up the wrong tree or worse yet, standing under it when the tree fell. Knox is extremely good at his analysis, though he seems to be perpetually behind on his translation duties, perhaps a result of there always being more piled in his in-box.
Knox is an Uzbek linguist, an expert thanks to "having lived in an Uzbek village in the mountains ... in Afghanistan for linguistic research, followed by further study in Uzbekistan when the Taliban grew too powerful". He "understood all dialects of Uzbek and could grasp related languages".