May You Die in Ireland — Michael Kenyon

The letter bearing the news that William Foley, easy-going math professor at a Midwestern university, had become the owner of a castle in Ireland was certainly cause for celebration. But the legacy that made him king of a castle also turned him into a human carrier pigeon, the unwitting bearer of a deadly secret.

It did not occur to Foley that the man at the travel bureau who was so accommodating was anything other than an extraordinarily friendly fellow…or that the black plastic airlines folder beneath his arm contained the key to that very lethal secret.

The professor was in high spirits as he boarded the Aer Lingus Boeing 707. He did not know that from the moment he set foot on the lush green of Irish soil, he would become a living time bomb.