The story describes Britain's need to update its naval preparations. Norland, a fictional small country in Europe has been fighting England and is now invaded by an English army. However, Norland has a naval flotilla of submarines commanded by Captain John Sirius. Sirius uses his submarines to lay a naval blockade around the British Isles, so that no supplies can be landed. Consequently, the British start suffering famine. Some of the submarines are sunk and the British are congratulating themselves, when Sirius, waiting outside Liverpool, purposely torpedoes a large White Star liner, the RMS Olympic. The British end up surrendering.