The Nazis were assisted both by active collaborators and ordinary citizens failing to act, as two powerful new books show.

In Bystander Society, historian Mary Fulbrook, drawing onan extraordinary archive of personal accounts, argues thatrather than what and when Germans knew, how they reactedwas key. In Safe Haven: The United Kingdom’s Investigations into Nazi Collaborators and the Failure of Justice, former BBC journalist Jon Silverman asks why, despite considerable expense and effort, the controversial 1991 War Crimes Act yielded just one conviction. In conversation with acclaimed journalist and KC Joshua Rozenberg.