Eep discovers fire for the first time. Fire allowed humans to fight, stay warm, consume healthier foods with more nutrients, and ultimately survive. Fire is one of the first discoveries that distinguished humans from other animals.

Chrome shows Senku a trick up his sleeve involving a fire and changing its color. While everyone else thinks its sorcery, Senku finds it unimpressive and explains what Chrome did is a procedure called the flame test.

The boys use the suction of three vacuum cleaners to retrieve a ball that is out of their reach. Their attempt fails when the "Beast" chomps down on a pipe, which blocks off almost all air flow to the suction.

Beakman explains what metals are and how they occur naturally. He then pretends to be Andrew Carnegie to explain how he figured out how to make steel. Beakman explains that steel is a lot stronger than iron so this allowed us to create buildings, strong machines, etc.

Disaster strikes in a New York tunnel as explosions collapse both ends of it; a combustion ensues.