England, December 1926. Although her personal life is in tatters, the famous writer Agatha Christie decides to leave everything behind to help unravel an unsolved murder committed on a train six years ago, unable to imagine the disproportionate consequences that such a selfless act will cause.
When Seb is offered a place on a radical retreat designed to solve the national crisis of teenage unhappiness, he is determined to change how people see him and make his parents proud. But as he finds himself drawn to the enigmatic Finn, Seb starts to question the true nature of the challenges they...