Gerald Humphries, better known as Hump, is a one-armed former army medic with a dark past. As a rum-runner who first transported illegal alcohol and then infants across the Detroit River, he lives on the edge of the law. When he meets and marries Polly, a prostitute from Detroit, together they become saviours to women in Canada, helping them with unwanted pregnancies and avoiding scrutiny from the authorities.
Under questionable circumstances, Sister Brigid has been transferred from Montreal to teach at Our Lady Parish school in Ojibwa, a small town in South Western Ontario along the Detroit River. When she meets Hump, now older and widowed, an alcoholic janitor living in the Back-End of Ojibwa, their paths collide in a way that could sent them both to prison.
Together, Sister Brigid and Hump take on the task of 'saving', while others-Gran, Collette, Melissa, and her best friend Anita have their own complex lives to live and decisions to make.
Set in Canada during the years of prohibition, back-street abortions, and baby trafficking, Little River Bridge connects the lives of those in the Back-End with those In-Town, where occurrences on one side have long standing implications on the other.