British nurse Edith Cavell (Anna Neagle) is stationed at a hospital in Brussels during World War I. When the son of a former patient escapes from a German prisoner-of-war camp, she helps him flee to Holland. Outraged at the number of soldiers detained in the camps, Edith, along with a group of sympathizers, devises a plan to help the prisoners escape. As the group works to free the soldiers, Edith must keep her activities secret from the Germans