Weapons designed for everyone are an advantage at war, but they can also be extremely devastating. Experts test the three most important weapons that can be learned quickly. The crossbow transforms peasants into warriors that suddenly become a threat to the knight; learning to use a pike is easy but requires bravery. The Kalashnikov is considered the world's deadliest weapon due to its rare simplicity, but if 3D printed guns go into mass production, world peace will never be the same.

War at sea: a new form of warfare with exceptional challenges. In this episode, weapons expert Stephen Bull tests three significant weapons of the sea. The Byzantines guarded the Greek fire as the secret super weapon that kept Constantinople safe for 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.