Father Unwin visits a health farm in order to keep tabs on one of the residents, a notorious spy named Sakov, and is baffled when Sakov manages to engineer the crash of a test car whilst secured in a treatment room.
A Russian saboteur, Sakov, arrives in England under the false name of Herr Vokas, claiming to be a patient in a nearby health farm. However, Father Unwin soon finds that Sakov is actually here to sabotage the test of an experimental fuel for the army for Tanks.—DanDud88