Former M15 head Eliza Manningham-Buller and Turkish author and commentator Elif Shafak discuss favourite books with presenter Harriett Gilbert. Choices of a good read are: Chimamanda Ngozi Adichie's latest, Americanah; Michael Chabon's ripping yarn set a thousand years ago, Gentlemen of the Road; and The War Between the Tates, Alison Lurie's dissection of a marriage breakdown.