Although they have a happy marriage, Sir Charles Chatham, an explorer, and his American wife, Lady Marion, have been unable to have children. After Charles goes to Egypt, his sister Gertrude and her sweetheart Stephen Hartley, an American consulate attaché, take refuge from a storm in a deserted tower. Frightened, Gertrude yields to Stephen's advances. Although he intends to marry Gertrude, Stephen suddenly is called to deliver supplies to starving women and children in Russia. Marion takes the