Who shows up at Harry's house in Chapter 11, and why?

Two detectives from Special Investigations show up at Harry's apartment, at the beginning of Chapter 11. They tell him that Karrin Murphy sent them to pick him up, and ask him to come to Micky Malone's house to help them with a disturbance there. They don't give him many details, but they convey the urgent nature of the situation, and Harry goes with them.