The Book of Kells Last Peril. As told by Aislin decedent of Brother Brendan of Kells. Long, long ahgo, in the days o ’ Celtic Irelahnd when Romahn. Catholicism was just beginning, a book was written in Iona by Brother. Aidan o ’ Iona. The Celtic deities o’ death, Cromm Cruiach ahnd the.