1938: Rani, the bright and spirited daughter of an Indian Crown Prince, leads a privileged if lonely life. Longing for freedom and purpose, she escapes the confines of her father's palace and meets Prasad - a poor young man - with whom she falls deeply in love. But her plan to gain her father's approval for the match disastrously backfires. Estranged from her family and haunted by guilt, Rani's path takes her from Cambridge to Bletchley Park and a new world of intrigue and secrets. Against the backdrop of war, Rani finds comfort and a sense of belonging with fellow codebreaker William and his young son. Could they heal her heart and become the family she craves? Then Prasad reappears - and past and present collide, shattering Rani's fragile happiness. As retribution for the hurt she caused him, he demands she pass him secrets from Bletchley. But at what cost? Torn between her past and her present, love and loyalty, Rani must face up to a heart-wrenching sacrifice...