The story centers around the character of Sir Nigel, an English nobleman, and his relationship with a young woman named Zara. The narrative unfolds over the course of a day, during which Sir Nigel and Zara meet and become romantically involved.Elinor Glyn's "One Day" explores themes of love, passion, and the societal constraints that impact relationships, particularly between individuals from different social backgrounds. The novel delves into the emotional journey of the protagonists as they navigate their feelings for each other amidst societal expectations and obstacles.The book is recognized for its romantic elements, the exploration of social class dynamics, and its depiction of the emotions and conflicts arising from a brief but intense encounter between two individuals. Elinor Glyn's writing style often emphasized passion and romance, and "One Day" is considered a representative work of her romantic fiction.