The team find out what makes food fit for a celebration. Helen Lawal finds out how tall a celebration cake can go. Jimmy Doherty unravels the secrets of a classic party food, the samosa; and investigates why there's so much air in a bag of crisps. Kate Quilton discovers how the shape of celebratory chocolates can change how they taste; gets her hands dirty helping a world champion create a sugarwork showpiece; and finds out what separates cordial from squash. Briony May Williams learns all about bags of ice, and how to really mix a martini and Matt Tebbutt dons a lab coat to explore the science of party food.