It's an alternate history. In 1870, Napoleon III meets with scientist Gustave Franklin who is developing a serum to turn animals into super soldiers. Two lizards escape and an explosion kills everybody. The young Napoleon IV signs a peace treaty with Prussia and thereby extending the Napoleonic age into the future. Scientists disappear and the world remains stuck in the steam age. Coal and Europe's forest have been used up. In 1931, the government is kidnapping any remaining scientists to prepare for impending war. The Franklin family is continuing their research into the invulnerable serum. Inspector Pizoni fails in their arrest and vows to avenge his demotion. The parents disappear after being attacked by a lightning black cloud. April (Marion Cotillard) escapes with her serum-altered talking cat Darwin. Ten years later, Julius is working for Pizoni to keep track of April and her grandfather Pops. April hopes to finish her parents' work and ends up uncovering a shocking conspiracy.
This is a fascinating world. The animation is interesting. It's comic book animation. I would stay with April more consistently and keep the reveal secret longer. Revealing the parents so early takes away some of the tension. It could be a more compelling shock. April needs more comedic scenes to add to her appeal. She's a little stiff. The talking cat could have been fun except for his sickness. Nevertheless, the overall sense is one of a good adventure.
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