Hugo and Nebula award winner Anderson incorporates two stories he wrote for the Asimov’s Universe series into this absorbing posthumous novel, a fast-paced space opera that never lets the reader forget that aliens are alien. At a time when nearly immortal humans have colonized the galaxy, various space-faring species commingle freely and the residents of Earth have become as alien to other humans as true ETs, an astronomical event that may affect all existence is about to take place. Unfortunately, only one set of aliens knows what that event is and their ruling dictatorship is hell-bent on keeping it that way. Lissa Windholm, an Earth woman with a spirit of adventure men find attractive, is determined to uncover the mystery and share the knowledge with everyone. Lissa and her partner Karl, a tyrannosaurus-like scientist, make some startling archeological discoveries on the planet Jonna about beings known as the Forerunners, but a psychologically scarred starship captain and an impressively ancient and profit-minded human rogue have other plans for the relics. Moving from one key sequence to another, Anderson omits much of the buildup and back story customary for such epic-scale SF, yet his protagonists and the worlds they explore always feel rich and real.