Harrigan preaches in front of 2 Hammarskjöld Plaza. He is ticketed by Officer Benzyck daily (it is presumed because he is known by Benzyck) because he doesn't have the required permit. He ignores the tickets and continues to preach.
In Song of Susannah, Harrigan helps Father Callahan and Jake Chambers track Susannah to the hotel where she left the Black Thirteen, telling them in which hotel she stayed. He also helped defuse the tension between Jake and the taxi driver that almost ran over Oy.