The Ninth Legion marched into Britain during the Claudian invasion and then, according to popular legend, disappeared without a trace somewhere in Scotland. Historian Tristan Hughes retraces its documented movements across the British Isles, from its landing to its last confirmed mention in the historical record, testing the vanishing story against what inscriptions, forts, and archaeology actually show. Dr Miles Russell, Dr Rebecca Jones, Dr Simon Elliott, Lucy Creighton, and Dr Andrew Tibbs walk through the evidence on location, including sites tied to the legion's presence in the Scottish midlands, weighing whether the Ninth was truly wiped out or simply reassigned and folded into other units elsewhere in the empire. The film treats the disappearance less as settled fact than as a myth built on gaps in the record, and follows the paper trail of tile stamps, building inscriptions, and troop lists that either support or undercut the legend. It is the first episode of a series examining the fate of the legion in detail.