Being sucker for Irish mysteries, I picked this one up. It's first in the Frank Pagan series. Pagan is a British cop sent over to the U.S. in pursuit of an IRA assassin, nicknamed Jig, who, in turn has been told to track down those who had stolen $10 million intended for the IRA. Throw in a psychotic Protestant minister with his own agenda and the FUV (Free Ulster Volunteers) and things get surprisingly messy with colliding agendas. Pagan and Jig are forced to link up in order to sort things out as ostensible IRA terrorism comes to the United States. To say more would ruin the surprises.
While I wouldn't say this was a favorite book, I will look for more titles by Campbell Armstrong, whose books are being reissued by OpenRoadMedia. Armstrong died in 2013.