This book, the second in Zola's Rougon-Macquart cycle, is so markedly different from the first that they could have been by different authors. Which is a very good thing, because the first was a bit of a struggle, and this was exceptionally good.
Zola intended to illustrate different aspects of French society with each novel - mining (Germinal), farming (La Terre), painting (The Masterpiece), courtesans (Nana), etc - and The Kill (La Curée) is about the reconstruction of Paris by Haussmann in the 1860s. While Paris is admired now for the straight boulevards and uninterrupted sightlines, which were designed by Haussmann, at the time they were controversial, and a source of corruption, speculation, great wealth created as ancient districts were destroyed to make way for the new roads. Zola saw all this as emblematic of the Second Empire, and depicted it in this novel.
It's a novel about transformation and transgression. France has recently changed from a Republic to an Empire, and now Paris is being transformed by these designs, imperiously ordered. To enable the building works, Paris sucks in workers from around France, further urbanising the country. And to finance the works, Haussmann engineers various smart enterprises, such as selling bonds to developers for the right to land alongside the new avenues. In doing so he creates a need for modern financial institutions, so France develops a more sophisticated banking system.
All this is the background to the novel, but essential to it. The main plot is sufficiently transgressive to sustain the book on its own. The main characters are Aristide Rougon, first encountered in The Fortune of the Rougons, his son Maxime by his first marriage, and Renée, his second wife, much younger than him, and whose dowry and marriage 'gift' enabled him to start his speculative enterprises.
Renée is highly sexually voracious, although not for her husband, who is mostly wrapped up in business and is unconcerned. Aristide and Renée's activities are placed in parallel - his financial transgressions, frauds and manipulations are comparable to her sexual affairs. She seeks an experience beyond the normal, and starts an affair with her stepson, who is only eight years younger and has been an intimate friend since her marriage to his father.
The affair itself is multiply transgressive. Not only the 'incest' (not technically as there's no blood relationship, but the term still applied), but Maxime is throughout described unequivocally as effeminate. Renée is boyish in appearance, with short hair, and very sexually assertive with Maxime, almost taking the man's role. Renée's closest female friends have an unhidden relationship - all this debauchery is, for Zola, one manifestation of the immorality of the Empire.
Apparently this book has long been one of the most popular of Zola's novels, for obvious reasons - a plot that involves incest, financial speculation and corruption that has regular and periodic topical relevance. On to the next volume.