The screenplay is based on the novel of the same name , written by Mary Ann Shaffer and Annie Barrows. Set in , the plot follows a London-based writer who exchanges letters with a resident on the island of Guernsey , which had been under German occupation during World War II. In , development began on a film adaptation based on Shaffer's novel. Initially, Kate Winslet was announced as the lead, with Kenneth Branagh attached to direct. However, both dropped out in February Buy from other retailers.