Persephone Hadley is a Cross, daughter of a prominent politician, while Callum McGregor is a nought. As best friends, their relationship is frowned upon by society, a secret from Sephy's mother, and not approved by Callum's family.Callum starts at Heathcroft, Sephy's exclusive school, previously inaccessible to noughts.
Although he is two years older, Sephy is overjoyed to find him in her class. But the majority of her classmates will not accept that she, the daughter of a leading politician, wants to associate with a nought.Their friendship goes from strength to strength as Callum's brother and father join the Liberation Militia, a violent organization supposedly aimed at promoting equality between the two races, and Sephy's mother becomes addicted to alcohol. They develop a more intimate connection.
Callum's troubled elder sister, Lynette, commits suicide.Only Callum knows this though as she leaves him a letter saying so Later, Callum's elder brother, Jude, and father, Ryan, are accused of a lethal shopping centre bombing; Callum is expelled from school and Ryan faces the gallows. Fortunately, with the help of a lawyer Sephy's mother hired, Ryan escapes hanging but must serve a lifetime in jail. Sadly, Ryan tries to escape and is killed.
Sephy finally convinces her mother to allow her to go to Chivers boarding school. As she has not heard from Callum for a week, she writes him a letter asking him to run away with her and uses Sarah, the housemaid, to send it to him. Callum has decided to join the LM and does not read the letter until just before Sephy leaves. Sephy concludes that their friendship is no longer as important to him as she thought it was, oblivious to the fact that Callum tried to catch up with her as she is driven away.
She returns from Chivers nearly three years later. Callum is now deep into the LM as part of the deadly Stiletto unit, having already stabbed a Cross civilian to death to reach sergeant rank. He is reunited with his brother who joins the unit, charged with organizing a mission.Sephy receives a letter asking her to meet Callum.
She does so, on an isolated beach. Callum kisses her but the meeting is a trap and the LM capture her for ransom.During her imprisonment,.