It's impossible to understate Mary Pat Kelly's achievement in her new novel "Galway Bay." An evocation of the Great Hunger and the mass exodus to America that followed in its wake, the epic scale of Kelly's canvas is a thing to marvel at. When blight destroys the subsistence diet of the Irish, two million refugees are forced by circumstances and a callous government to make a journey to a new home. In Galway Bay we meet Honora Keeley and her husband Michael Kelly, fiercely independent souls determined to make the most of their fates. Spanning 60 years, Kelly's novel shines a brilliant light on the impressive heritage of the 40 million people who claim Irish ancestry here. Few authors combine her mastery of the history with her understanding of the people, her eye for irony and her ear for poetry make this a rich and rewarding saga. Grand Central, $26.99