War at sea – a new form of warfare with exceptional challenges. Weapons expert Stephen Bull tests the most significant three weapons of the sea. The Byzantines guarded the Greek fire as the secret super weapon that kept Constantinople save over 800 years. Experts build an original replica for an experiment that will demonstrate the thunderous force of a ship cannon. One of the most devastating missiles ever invented is the torpedo. And a subsonic torpedo might be ruling sea battles in the future.