After Michael Poole vanishes while experimenting with wormhole technology, a desperate signal from the end of time reveals that he has discovered a cosmic structure capable of altering the fate of the universe. The narrative follows the remnants of humanity as they attempt to decipher the mystery of Poole's disappearance and the nature of the immense artifact he encountered. Faced with the inevitable heat death of the universe, the characters must navigate the physical and logical constraints of space-time manipulation. The story unfolds through a grand-scale perspective, blending hard science concepts with the existential dread of a dying cosmos.

This work is widely regarded as a definitive example of hard science fiction that pushes the boundaries of scale and scientific speculation. Readers often note the immense ambition of the narrative, which successfully bridges the gap between human-scale drama and the vast, cold reality of the end of the universe. The technical density of the prose is frequently cited as a hallmark of the author's style, demanding close attention to the mechanics of the cosmic artifacts described. While some find the focus on physics over character development challenging, the consensus highlights the book's success in evoking a profound sense of cosmic wonder and existential scale.