Time Team investigate a huge hill near Cardiff that may be immensely significant; is it the long-lost Iron Age capital of South Wales? During the course of their investigations the archaeologists make one particularly rare discovery: the most complete Early Iron Age cup ever found in South Wales, which proves that the site is from the earliest part of the Iron Age, at around 800BC. A huge hill dominates the Ely housing estate in Cardiff. Its towering ramparts and deep ditches identify it as a hillfort, and the effort of their construction indicates that this was no ordinary Iron Age homestead. The site's so big that thousands of people could have lived up here. It's never been explored before. If there were houses, none are visible now and the age of the fort has always been a mystery. Tony Robinson and the Team have five acres of hilltop, half a mile of ramparts and ditches and just three days to answer some very big questions. Fortunately local residents are keen to help, and finds such as jewellery and fine drinking vessels show that Iron Age domestic life in the area was rich and colourful. But finding any houses is harder than anyone imagined and provokes fierce arguments amongst the Team as time ticks away. But the hours of careful scraping and one spectacular find do pay off, revealing that Cardiff's hillfort is as old and as important as anyone could have hoped.