This time, Richard Hammond looks at the weight of liquids. Richard joins one of his lab rats at his top secret test facility to discover what happens when a tonne of water is dropped on to a car from a height of 30 metres. Meanwhile, in his underground laboratory, Richard asks the two teams of young scientists to attempt to guess how much his security guard Ninja Nan and one of his lab rats weigh. But because this is Blast Lab, there's a twist... Ninja Nan and the lab rat have to sit on giant scales, while the contestants must use bottles of water to guess their weight.