England, 1848: A huge, civilisation-ending meteor, Astraea, is on a collision course with Earth. Outside of the British establishment no one knows... except a downtrodden young woman named Sarah Buckman. Desperate and alone, Sarah teams up with enigmatic Frenchman Jacques and a band of anarchists and criminals called the Lambeth Rats. Their plan is to tell the world of the coming disaster but sinister government agents - Hushers - dog their every step and plan to silence them for good.