Agatha Oddlow's set to become the youngest member of the Gatekeepers' Guild, but before that, she's got a mystery to solve! There's been a murder at the British Museum and, although the police are investigating, Agatha suspects that they're missing a wider plot going on below London- a plot involving a disused Tube station, a huge fireworks display, and five thousand tonnes of gold Bullion. A second mystery for thirteen-year-old Agatha Oddly.