The Annals of the Heechee

In the finale of the Heechee Saga, Robinette Broadhead, now a machine-stored personality enjoying a hedonistic afterlife among other machine-beings, faces an existential crisis when a powerful alien race resurfaces, threatening the annihilation of all intelligent life. Despite his vast knowledge and virtual immortality, Robin struggles to find a way to confront this looming danger, leading him to consider a direct encounter that could dictate the fate of the universe.