The Navy has its new submarines and must discover what to do with them. They cannot fall back upon Nelson as a precedent, and Their Lordships of the Admiralty are at a loss to create a strategy.

Gilbert Maltravers is given a new E Class boat and sent off to the Mediterranean, in the hope that the Admiral Commanding there will find something useful for him to do. He leaves his new wife behind and sails off to do his duty, hoping that somebody will know what his duty should be.

It is the end of 1914 and the Navy has suffered humiliating defeats. Something must be done.