Gavin is spending the COVID-19 quarantine in a small flat in south Dublin with his 80-year-old mother, whose mind is slowly slipping away. He has lived most of his adult life abroad and has returned home to care for her and to write a novel. But he finds that all he can write about is her. Moving through a sequence of remembered rooms - the 'cells' - Gavin unspools an intimate story of his upbringing and early adulthood: feeling out of place in the insular suburb in which he grew up, the homophobic bullying he suffered at school, his brother's mental illness and drug addiction, his father's sudden death, his own devastating diagnosis, his struggles and triumphs as a writer, and above all, always, his relationship with his mother. Her brightness shines a light over his childhood, but her betrayal of his teenage self leads to years of resentment and disconnection. Now, he must find a way to reconcile with her.