Wing Commander Marsh assists the British doctor as an orderly and he proposes escaping by feigning mental illness in order to be repatriated. The escape committee is not told of the plan and Marsh starts acting irrationally – however, the ever suspicious Ullmann appoints Private Hartwig to watch Marsh. Hartwig has a mentally disturbed brother and knows exactly what to look for. Will the wing commander be able to live the part and convince him?
