the Twins by Tessa de Loo (1993)
Anna and Lotte are twins born in 1916 in Cologne. After their parents die, at the age of 6, they are separated and Lotte grows up in the Netherlands, while Anna stays in Germany. They don't see each other again, except on two brief occasions, once during the war and once after, until they suddenly meet each other at a peat bath in Spa, Belgium, 70 years later.
The meeting brings up painful memories for both sisters, and they tell each other stories, mainly from when they got separated and until World War II ended. It is easy to see that the sisters hold a grudge against one other, and that the war has made them enemies.
This is one of those stories which suck you right in and keep you there. I loved it from the beginning to the end, and it is such a fascinating read. I really like how the war is the background, and how Anna and Lotte blame each other sides for letting Hitler carry on. The history of Anna was the one which I found most interesting as I haven't read much of ordinary life in war-time Germany before.
A definite must-read if you're interested in European history or just want a really good story. I have put the film version (and another book by Tessa) on my wish list.