Twins Scarlett and Thomas have been learning about the Victorians at school. Their grandad lets them use his time machine to travel back. Scarlett finds herself accompanying none other than Princess Victoria to the grand opening of the Great Exhibition. Alongside the royal family, Scarlett gets to marvel at the amazing glass structure and the inventions from all over the world.

Thomas befriends Jenny, daughter of the revolutionary Karl Marx, together they try to sneak into the Great Exhibition, but it goes very wrong when they tumble through a window into the ladies toilets and, after much screaming, are marched off to prison by the guards.

Will Scarlett ever be able to persuade the genteel Princess Victoria to go to the prison and free Thomas?