On an evening in 1846 engaged couple Meg O'Connor and Rory Quinn join in an exuberant moondance. Observing is the parish priest, Father Brian O'Malley. The moondance brings bittersweet memories of Siobhan, the long-dead love of his youth, with whom he still feels a spiritual connection. Within days of the dance, the villagers of Kelegeen awake to find their potato crops destroyed by blight. They've been through famine before. But this is an Gorta Mór, a monster the likes of which Ireland has never seen.

At first Meg and Rory devise ways to help provide for their families, Meg through her sewing, Rory with his wood carving. But when tragedy and a costly mistake end those means of survival they turn to more dangerous ventures.

Father O'Malley reluctantly teams up with an English doctor, Martin Parker, to alleviate Kelegeen's suffering.

When Meg learns of ships carrying Irish passengers to a new life in America she is determined to go and bring Rory and their families after her. It will take all her strength and courage along with the help of her beloved priest and the English doctor to make the plan succeed.