Throughout the 19th century, Irish Catholic immigrants have sought refuge in Boston after the Great Famine in Ireland also known as the Potato Famine of 1845-49. Even to the present day, Boston still holds one of the largest populations of Irish-Americans in the United States. Irish immigrants greatly influenced the Boston state, leaving great marks of their culture. South Boston is one of the neighborhoods that are historically known as a working class Irish-American neighborhood. As their numbers grew, they took pride in being involved with politics and taking political control of the city. The Kennedys are the famous dominant political families that are from Irish-American descent. Dennis Lehane, son of Irish immigrant was born August 4, 1965, in Dorchester, Massachusetts, another working-class neighborhood in Boston. Growing up in Dorchester in the 1970’s, the author witnessed his close-knit, insulated neighborhood undergo radical changes that were violent at times, but still retaining its core values (site). The novel Mystic River is set in the very same city and neighborhood that author grew up in and eventually returned to at the end. This essay explores the novel and the film ‘The Mystic River’; a story that focuses on the effect a crime has on three friends, as well as a working-class Boston neighborhood. The novel is effective in historical terms because it parallels the author’s vision Here we see the historical context in the author’s novel, his credibility gives his readers insight