Life is rough in the coal mines of 1876 Pennsylvania. A secret group of Irish emigrant miners, known as the Molly Maguires, fights against the cruelty of the mining company with sabotage and murder. A detective, also an Irish emigrant, is hired to infiltrate the group and report on its members. But on which side do his sympathies lie?

A woman finds a romantic letter in a bottle washed ashore and tracks down the author, a widowed shipbuilder whose wife died tragically early. As a deep and mutual attraction blossoms, the man struggles to make peace with his past so that he can move on and find happiness.