This continues the story began in Revelation Space, the first book in the series, but it takes place many years afterwards. Because there is no faster-than-light travel in this universe, the narrative by necessity must take quite a bit of time while character travel between worlds. Often there are disparate storylines that meet up at the end of the book as the events converge to the climax.

The Inhibitors--also known as "wolves"--have discovered humanity and proceed to dismantle the Resurgam system prior to wiping out all of the humans on the planet. Although they possess the power of simply destroying the world, the Inhibitors' plot is much more insidious and ultimately destructive. Fortunately, their convoluted plan gives the humans on the planet just enough time to escape aboard a "lighthugger" ship. This ship also carries within it terrible weapons of destruction, though their use against the Inhibitors is subject to debate. The weapons themselves possess sentience of a sort and have their own agenda. We also find out the ultimate goal of the Inhibitors, which is not at all what humanity expects. Turns out the Inhibitors are planning for something much, much WORSE than the rise of competing sentience and their plan is a long, long term scheme (on the order of billions of years) to save the galaxy as a whole.

Although all three of the Revelation Space novels I've read have their strange moments, Absolution Gap is by far the strangest. A sole survivor on a far distant moon orbiting a gas giant witnesses the planet disappear for just a second. During his dying moments, Quaiche has a divine revelation about his experience. He survives--barely--and creates an entire religion around the fact that the gas giant periodically vanishes for mere moments.

Meanwhile, lightyears away, refugees are fleeing the Inhibitors, guided by a strange little girl born with unusual gifts. They believe that the last hope of humanity lies within the gas giant system with a mysterious disappearing planet. Their only sign is that they must speak with "the shadows," mysterious entities believed to be whispering to us from the depths of hidden dimensions.