Heym himself has described some of the circumstances under which he came to compose Hostages. Although it was written in response to the American liking for detective stories, Heym wanted to write a detective story with a difference: he therefore decided on a plot in which the detective did not emerge as the victor. With his family's own experience of persecution in mind, he chose a Gestapo detective, set the story in Nazi-occupied Prague (a city of which he still had clear memories), and focussed on the resoluteness of the Czechs in fighting against tyrannical occupation forces. Such a plot gave scope for idealism, heroism, and also for a warning against National Socialism.

Traditional expectations of the thriller are not followed: the reader learns at an early stage that the dead man was not murdered but committed suicide, and we are provided throughout the text with much information the detective himself does not possess. We are thus placed above rather than behind this sinister Nazi, in terms of our knowledge and also morally. It is his investigation of his ‘suspects’ and their contacts which provides the framework of the novel, but the tension is provided by our emotional involvement with the Czech underground forces (one of whose members is a suspect), and the question of whether they will manage to blow up a supply of munitions destined for the eastern front.