Telling the story of cousins Anja and Monika through diary entries and letters, Dan Smith carefully shows the reader what life in Cold War Berlin looked at felt like through the eyes of a child. At the beginning the book reads simply - like a kind of 'Zlata's Diary' of East and West Berlin, but there is a cleverly crafted narrative at work that builds in pace as the stakes get higher.  When Anja finds a way to cross under the wall to Monika's side of the street, in East Berlin, she is observed by an informer and finds herself trapped. Hiding in Monika's flat, she is nearly discovered twice and suffers with claustrophobia as she is forced to conceal herself behind a secret panel in a wardrobe. Meanwhile, Monika is being pressured to betray her parents and Anja with promises that if she gives up information about a planned escape to the West they will go free. The cousins' friendship is destroyed by the regime in the East, and it is chilling to read. Both girls are left with the trauma of each thinking that their eventual discovery was their fault - until, at the fall of the wall in 1989, they meet again.

This is an extremely clever book - one that puts in sharp contarast the innocence of children and the darkness of the oppressive regime that seeks to control their lives. It is unsettling, thought provoking, brilliantly pitched for 11-12 year olds - and in the end, a book that celebrates the power of forgiveness.