Kate investigates alternative milks. At one of California's leading producers of almond milk, she finds out how many almonds make it into each bottle; before meeting a scientist who's been raising genetically engineered goats whose milk he hopes might one day save half a million lives every year. Jimmy investigates reports that some of the fish we buy may not be what we think. At a remarkable bunker in Oxfordshire, he joins a team of agents who monitor every vessel in the world's oceans and detect any signs of suspicious behaviour. Then Jimmy hooks up with a fish detective in Edinburgh, on a covert mission buying and testing fish to make sure it's the real deal. And what exactly is spreadable butter? Is it butter or margarine? An extraordinary award-winning butter sculptor helps Matt find out.