In May of 1942, Peter has assumed the position of the organist at a small church in Velsen. On Sunday, May 10th, the ten Booms go to a service at the church to hear him play. After the conclusion of the service, Peter begins to sing the national anthem, which inspires the rest of the congregation to rise up and join him in singing. The German police, who have occupied the Netherlands, arrive three days later to haul Peter away to a federal prison in Amsterdam.
Peter has remained in prison for two weeks when Mrs. Kleermaker, a Jewish woman, comes to the ten Boons seeking refuge. The ten Boons end up becoming part of the underground movement to shelter Jews from the Gestapo. After a total of two months in prison, Peter is eventually released and begins his own form of resistance work once again.