1906. HMS Dreadnaught, Britain's latest Battleship lies in her moorings in a Portsmouth dockyard awaiting her Sea Trials. Her design and armament renders the current warships of other Nations obsolete. Secret items of novel yet vital radio detection equipment are stolen from her hold by agents of a foreign power. Holmes is requested by Military Intelligence to determine the perpetrators and trace the existence of the stolen items before they may successfully be removed out of the country. His investigations reveal the existence of an old and implacable enemy. Secrecy is paramount. Public knowledge of the crime would possibly result in a European war of disastrous consequences.