A flood is an overflow of water that submerges land that is usually dry. In this episode, the team investigates the devastating effects of this phenomenon. Mike heads to Southampton to learn all about the most important flood rescue vehicle: the hovercraft. Clare goes to Boscastle to meet the survivors of a flash flood that happened in the United Kingdom. Zoe and Leo find out what it's like to be trapped in a car during a flash flood. Part of the "Fierce Earth" series.