Trelane (of the TOS episode "Squire of Gothos"), who turns out to be a young member of the Q-Continuum, taps into the ultimate energy source and uses it-or is used by it-to tamper with the nature of reality and the flow of time. Q and the crews of the starship Enterprise from three parallel universes find themselves right in the thick of the action.
Three things seem apparent about this novel. First, author Peter David had fun writing it. It's clever, if a bit too convoluted at times, and has fun making unexpected connections and arcane references to Trek history. He has a firm grip of the characters and writes their dialogue and interactions well. Second, he wrote it fast, much too fast. The prose is very sloppy, becoming at times unreadable. Third, this book is much too long. Most, if not all, of the sequences written from the perspectives of Q and Trelane should have been cut out. That would have improved the novel a great deal, because those scenes are truly awful.
Here's the problem: how can anyone, much less a guy dashing off a Star Trek novel, convincingly inhabit the perspective of an omnipotent, omniscient being? A masterful novelist might pull it off with great thought and effort, but Peter David isn't up to the task. That's not a knock against him, since almost nobody is up to that task, but he should have realized his limitations. He gives us beings who, rather than existing on a plane beyond our understanding, have mothers and fathers just like we do, act from very human motivations, and even derive their names from Latin root words! The TV series managed (just barely at times) to present the character successfully because it was always made clear that the version of Q and his universe that we saw was dumbed down to make human comprehension possible. David mistakes the dumbed down version for the real, unvarnished thing.