When Sardar Singh Jatav set out walking on a muggy night in early September to talk with the men who employed his son, he found them already waiting for him in the road. But they were not in the mood for discussion. The higher-caste men greeted Mr. Sardar with a punch to the face. Then they broke his arm. Then they pinned him down. Mr. Sardar shrieked for help. Nobody came. One higher-caste man stuffed a rag in his mouth. Another gleefully pulled out a razor. He grabbed Mr. Sardar’s scalp and began to lift and cut, lift and cut, carving off nearly every inch of ...