Young up-and-coming lawyer Adanna learns that her father, newly diagnosed with dementia, has gone missing. She is quick to pass the message to her three friends, who are bound together by a terrible secret.

The four have been a close-knit group since the age of nine. Adanna, smart but shy, quiet, and reserved, was born to a doting professor father and a strict senior civil-servant mother. Ifenkili, the leader, is the glue that holds everyone together, her boldness concealing shame over her poverty and her envy of others. Okey, nicknamed Oyibo Pepper, is a young albino boy, academically bright. Last is Ikechukwu, nicknamed IK, a boy dedicated to fun and enjoying his wildness.

The four of them gather often in Adanna’s beautiful home, but there are rooms that are out of bounds. At Ifenkili’s prodding, one day the children gain access to them and discover Adanna’s secret: her twin Nwamaka, who suffered severe brain damage at birth and is unable to speak, walk, or do much of anything. One of them feeds her a palm kernel, and she chokes on it. Adanna hurries them out, but delays telling anyone what happened for fear of her mother. By the time Nwamaka is discovered, it is too late.

The children carry their secret with them for the rest of their lives. Written in revolving perspectives from all four protagonists, Adanna’s Secret follows their lives across Enugu, Lagos, and Halifax, Canada. It explores disability and shame, friendship, bullying, living with albinism, university elitism, parent/child relationships, spirituality, and ambition, against the political and historical backdrop of Nigeria from the 1980s to the present day.