The ancient Roman town of Pompeii lies in the shadow of Mount Vesuvius, but its inhabitants are blissfully unaware of the deadly threat of the volcano that is about to devastate their lives. Still on the hunt for their missing parents who are lost in the pages of history, twins Jemima and Joe Lancelot travel back into the past once again, along with best friend Charlie, and Max their talking Tonkinese cat. When the children arrive in the middle of a slave auction in the Forum, they are shocked to find themselves being sold to the highest bidder. Trapped in the household of a wealthy Pompeian, how will they manage to escape before the town is buried by the erupting volcano?