Lone Star Planet by H. Beam Piper

It was early evening before we finally managed to get away from the barbecue. Thrombley had called the Embassy and told them not to wait dinner for us, so the staff had finished eating and were relaxing in the patio when our car came in through the street gate. Stonehenge and another man came over to meet us as we got out -- a man I hadn't met before.

He was a little fellow, half-Latin, half-Oriental; in New Texas costume and wearing a pair of pistols like mine, in State Department Special Services holsters. He didn't look like a Dumbarton Oaks product: I thought he was more likely an alumnus of some private detective agency.