In Britain at the turn of the 20th century, a female astronomer tries to avoid the patriarchal attitudes of the day. 

Set in London in 1910 brilliant and headstrong Katharine Hibery (Haley Bennett) resists her parents plan for marriage, determined to instead pursue her passion for astronomy. When her controlling father, Mr. Hilbery (Timothy Spall), forces her into an engagement with family friend William (Jack Whitewall), Katharine's carefully guarded independence is threatened.

Her world begins to expand when she befriends spirited suffragette Mary Datchet (Lily Allen) and crosses path with working-class editor Ralph Denham (Elyas M'Barek), who is assisting her mother, Mrs. Hilbery (Jennifer Saunders) with a family biography. As romantic loyalties shift, Katharine is pushed to question everything she has been taught about love, ambition, and how to claim her space in the world.