From the barren rocks of Aden to the west coast of Ireland, the war under the sea is subverting the certainties of the Victorian Navy. While the dreadnoughts hide away at Scapa Flow and Kiel, the submarines and small ships of both sides are taking the war to the enemy coast. The Royal Navy is at war with itself and, as in any civil war, the conflict is merciless.

Gilbert Maltravers takes his tiny E Class boat to war against both navies in this final book of the trilogy.