Scientist Nina and her young experimenters discover the amazing ways that things can change and react in our everyday world. Nina investigates what fire is with the help of Felix, her touch neuron. Experimenters Diarmuid, Mia and Ronan visit Nina in her lab and, using their senses, discover that fire has colourful flames and that fire gives out heat and light. Then Nina does an experiment to show us that fire needs oxygen to burn. Next they visit a forest to find out what else fire needs and they find out all about different types of fuel. Finally back in the lab, the children discover that when you mix certain things together they react and make heat and that mixing oxygen with a fuel makes fire.