Following a controversial loss at the Purley Cup, Poppy Orpington and her petrol-fuelled race car, Thunderbus, are dominating the headlines. But not one article is complimentary, or even unbiased. In spite of these daily slanderous reports on her character, Poppy is determined to make something of herself. She continues racing, she starts up her own factory hoping to sell her father's patented petrol-run cars, she buys her own house and speaks up for the down-trodden. But all the while she is still seen as just a woman. A woman unwilling to squeeze into the female mould created by men of power – and so the mould must be broken.

In a world that refuses to let her move forward, can Poppy stay ahead of the pack? In an alternative Edwardian era, steam-powered marvels are a common occurrence. Airships fill the sky, steam-powered automobiles race across the land, and television, computers and are already an emergent technology. However, these inventions are only for a privileged few, as those lower down the social ladder struggle to get by without even the most basic of necessities. Sixteen-year old Poppy Orpington seems destined for a life of near-poverty until her father perfects a petrol-fuelled racing engine. Their early successes allow Poppy to gain a new prosthetic arm, allowing to her to gain the mobility she's desired all her life. But can a working class family crack open the aristocratic world of motor racing? Can Poppy overcome prejudice and social conformity as she fights to find a place in the world? Or will the ruling elite crush her only chance of a better life?