Peter Neilsen was a redheaded young Danish man who had been engaged to Annemarie's sister, Lise. Peter had been like an older fun-loving brother to Annemarie and her sister, but after Lise's death, he changed. He rarely stopped by their apartment to visit, and when he did, he was rushed and serious. Sometimes he brought Annemarie's parents the De Frie Danske, an illegal newspaper backed by the Danish Resistance. The Danish Resistance was a group of courageous young people who secretly organized operations to bring harm to the Nazis and lead the Jewish people to safety.
Peter was instrumental in organizing the plan to help the Rosen family and the other Jews escape Nazi-occupied Denmark. While Ellen spent the night at the Johansens, Mr. and Mrs. Rosen were in hiding with Peter.
At the end of the novel, we learn that Peter was captured by the Germans and executed in the public square in Copenhagen. Peter died for what he believed — "he was proud to have done what he could for his country and for the sake of all free people."
