This month Harriett Gilbert talks to acclaimed American writer Lionel Shriver.

Her prizewinning novel, We Need to Talk about Kevin, is the profoundly disturbing story of a boy who, shortly before his 16th birthday, kills seven classmates in a high school massacre.

Grippingly but unreliably narrated through the letters from his mother to his absent father, the novel raises questions about culpability, the limits of maternal love and the nature of evil itself.