It is 1845. The elderly French emperor Napoleon, having defeated the British at Waterloo, is now preparing to crush his old enemies once and for all. His secret weapon: a titanic airship, cloaked in an Aetheric Shield, that will spearhead the invasion of Britain. In the forefront of Britain's defence are the Sky Sisters, a crack team of intrepid aviatrixes led by 18-year-old Lady Arabella West. Sent to investigate reports of a giant mechanical eagle that is capable of snatching an airship in its talons, Arabella finds herself in a situation where she will need all her courage and ingenuity to survive.