This is not a trilogy of three independent stories; it is a book chopped up into three parts with cliff-hangers for the endings of the first two.
It took me a few tries to get into The Golden Age, because this is a story of the far-distant, transhumanist universe. Sophotects -- immensely powerful AI -- humans who have rewired their minds to connect their conscious and subconscious in various configurations, Cerebellian minds that consist of many, many, many living organisms -- even "basic" humans have the ability to remove memories or alter their personalities, or create "partials" that will do their work for them and be reassimiliated back into the original mind. (Primitivists don't, but they could if they wanted to.) Noemic recording allow people to have their minds and characters records so they can be revived. People can devise and share dream universes. The Cacophiles, the Nevernexters, resent that they will never receive an inheritance because their parents will never die. People routinely use translators to accommodate their very different brain structures in communication, and sense filters to make their environments appear as they wish.
Once upon a time, there was a extra-Solar colony at Cygnus X-1 to harvest the power of its black hole, but it fell silent. Human life is found in the Solar System -- but all over the solar system. Jupiter has been imploded to set off hydrogen fusion. The mischievous Neptunians live in the farthest reaches, for its poverty, for the chance at freedom and solitude; they are notorious for such stunts as viruses and mindworms. Venus has been terraformed, the Sun is being tamed by the Solar Array, and the once-in-a-thosand year Transcedence is approaching.
And in the middle of this, Phaethon wanders through a grove of genetically engineered trees that turn their leaves to where Saturn would shine, if it shone brightly enough, and an old man there jeers about "that reckless boy, what's his name, that Phaethon" -- something Phaethon has no memory of. The old man vanishes in a manner Phaethon finds rude, and so he tries turning off his sense filter to find him again. He learns that he has, for some reason, set his sense filter to block out Neputanians -- but with it off, he sees one. It pleads with him to come and let it free him from what has been imposed on him.
His investigation reveals that he is missing memories. Large chunks of them. Centuries of them, and he's only a few thousand years old. He could restore them -- but, he is warned, at the price of exile. His wife Daphne drops out of a dream-world competition to plead with him and, in an attempt to stop him, reveals the truth -- that she is not really his wife, who drowned herself in dreams, but an emancipated partial of her, changed to be more suitable. And he learns that he is suing his own father, Helion, with a claim that his father is actually dead. Something happened between the last noetic recording of him, and the last version's death, that meant that the recovered Helion was not the same man. Or so he is claiming. He doesn't remember any of it.
It gets even more complicated from there. Intrigue, the College of Hortators and exile, violence, the last soldier in the Solar System, an amazing ship, questions of identity, morality, individualism, and survival. The horrors of letting everyone do as they please as long as they do not use force. Love and reconciliation and really, really, really cool toys.