The d'Alemberts, a family of spies, thieves, and revolutionaries working for Empress Stanley Nine of the Empire of the Earth, learn that their planet Omicron has been conquered by aliens and they team up with treacherous Lady A to stop them
Edward Elmer Smith (also E.E. Smith, E.E. Smith, Ph.D., E.E. “Doc” Smith, Doc Smith, “Skylark” Smith, or—to his family—Ted), was an American food engineer (specializing in doughnut and pastry mixes) and an early science fiction author, best known for the Lensman and Skylark series. He is sometimes called the father of space opera.
This is the ninth in a 10 novel series which was mostly written by Stephen Goldin. Doc Smith wrote a novella called Imperial Stars which Goldin expanded into the first novel, and then Goldin wrote another 9 novels in a long story arc. But Smith is the famous one, so his name appears in large letters everywhere and Goldin is barely mentioned.
The setting is a universe where a Russian Feudal system has somehow become the dominant mode of government and of the language, so we see Russian words sprinkled throughout the conversations. Humanity has spread to a number of planets with varying characteristics. One of these is DesPlaines, a high gravity planet whose inhabitants have adapted by becoming shorter and stockier, and which has developed a unique attraction, The Circus of the Galaxy. What people don't know is that this circus is also a key part of the secret service SOTE, the Service Of The Empire. This allows for an interesting twist for space opera, a series where the heroes do not have secret weapons or super powers, merely acrobatic training.
Lady A. comes to the government with deadly news. The planet Omicron has been invaded by an alien menace which is intent on wiping out the human race. She says they must join forces to confront this enemy and proposes a truce for the duration. But can she be trusted? Is this what it looks like, or just another twisted plot? But Jules and Yvette d'Alembert, top agents of SOTE, and their friend Pias Bavol, have to unravel this plot and save the Empire. The book is fast-paced and a good combination of space opera with spy thriller. But since this a 10-novel story arc, each novel builds on what went before, so do not read them out of order.
The Omicron Invasion forces our favorite space spies to do the unthinkable—make a deal with the literal devil. In this ninth and penultimate book of the series, word reaches the capital that Omicron, the most far-flung, distant planet ever settled by humanity, has been completely overrun and devastated by a mysterious alien invasion. SOTE is panicking because an intergalactic war is brewing on the horizon. Things are so desperate that our super-strong circus heroes, Jules and Yvette d'Alembert, have to sign an alliance of convenience with their absolute arch-nemesis, the treacherous and deadly Lady A. Accompanied by Lady A's henchmen and a sharp naval intelligence captain, the twins load into a starship and head into the deepest, unknown dark to see what's left of the frontier. Watching Jules and Yvette try to fight off a terrifying extraterrestrial threat while constantly watching their own backs to make sure Lady A doesn't slip a knife between their ribs is pure gold. It shifts the series from standard empire-spying into a grander, edge-of-your-seat survival mission with massive stakes.