Long Day's Journey INTO Night is a play written by American playwright Eugene O'Neill in 1941. It is widely considered to be his masterpiece and one of the finest American plays of the 20th century. The play is semi-autobiographical and tells the story of the Tyrone family, a family struggling with addiction, financial difficulties, and the death of a child. The play is set over the course of one day and is a powerful exploration of the human condition.