Mary Margaret Kincade, a young lass from Cork, Ireland faces an uncertain future when her father's expedition goes missing in the Arctic Circle. Determined to make a new start, she signs on to the Mauretania to work her way to America.
After witnessing his closest friend being murdered by English soldiers, Liam Cormac joins the Irish Brotherhood. He spends some time in an Irish prison after the Easter Uprising. A plan of revenge on the English is hatched and Liam takes a position on the Mauretania as a bartender in order to accomplish the mission.
The plan to blow up the ship in the middle of the Atlantic Ocean is uppermost in Liam's mind. Disowned by his family, he doesn't care that he's on a suicide mission. When he meets the lass from Cork, the stakes change and he rethinks his goals, but his co-conspirator pressures him to move forward.