Once again Merriman is involved in the murky world of secret agents with English spymaster Mr. Grahame, a man he knows well, to find out what they can about the French plans in Ireland where Merriman’s old enemy Moreau, a French agent, appears once more. This is a rousing story about murder, fights with the French at sea, and ashore with the background of the real French invasion of Ireland which was attempted, but failed.