A Game of Sorrows: S. MacLean

It is 1628, Charles 1 is on the throne, and the British Crown is finally taking control of Ulster.
Returning to his rooms one night, Alexander Seaton is shocked to find a stranger standing there - a man who could be his double. His name is Sean O'Neill, and he carries a plea for help from Maeve O'Neill, forbidding matriarch of Alexander's mother's family in Ireland. All those who bear their blood have been placed under a poet's curse: one by one they are going to die. Only Alexander is immune, his O'Neill heritage a secret from all but his closest family.
Alexander travels to Ulster, to find himself at the heart of a family divided by secrets and bitter resentments. As he seeks out the author of the curse, he becomes increasingly embroiled in the conflict until - confronted with murder within his own family - his liberty and, finally, his life, are at stake.