A Dozen in Denver

In this short story a private investigator is hired to find out who “killed” and old servant bot by smashing his head with a pipe. He takes the case just to tie him over the dearth of his usual customers, suspicious people looking for dirt on their cheating spouses. His snooping leads to the conclusion that another robot is the culprit, which is not possible as robots are non-violent machines, or that is what the powers above say. His suspicious are confirmed when he finds and confronts the culprit bot, a rather non-compliant and violent machine. The social order as he knows it becomes suspect.