Queens and pirates

"In a time when the Industrial Revolution has become an all-out war, Mad Science rules the World...with mixed success. Agatha is the last of the Heterodynes--a notorious family of Mad Scientists that everyone had thought safely wiped out. Now, the ancestral city of the Heterodynes has been trapped in a bubble of stopped time, and Agatha is on a journey to find a way to reverse the effect and save the people she loves. In this volume, Agatha and her friends have just helped the independent city-state of Paris fight off an invasion. Now, they're off to Londinium, a marvellous glass city beneath the sea, in search of a time manipulation device built hundreds of years ago by the legendary spark Van Rijn--but will the ancient God Queen who rules the land be willing to help free Mechanicsburg, the home of the utterly evil (until-very-recently) Heterodyne family?" -- back cover.