A blend of fact and fiction, Kate and the Composers follows Kate Bourke, a young girl who emigrates from Ireland with her family to make a new life in Toronto in the late nineteenth century. After leaving school in Grade 8 to help support her family, she works as a maid and then a proofreader, but harbours a secret desire to become a writer. Music is her north star, and Kate draws inspiration and consolation throughout her life from her Uncle Frederick's popular song, "The Flight of Ages." Her marriage to a flautist and composer who is starting a musician's union brings a new set of challenges while she tries to pursue her dream.