One of the funnier Star Trek novels with "Captain" Dr. McCoy in charge, anything (and everything) is liable to happen (and it does!)
When Dr. McCoy grumbles once too often about the way the Enterprise ought to be run, Captain Kirk decides to leave the doctor in command while he oversees a rountine diplomatic mission. Kirk beams down to a strange planet nicknamed Flyspeck to negotiate its admission into the Federation, leaving Dr. McCoy to enjoy his new authority. However, the doctor soon learns that command is a double-edged sword when Kirk disappears without a trace. Desperately trying to locate his catain, McCoy comes under pressure from Starfleet to resolve the situation immediately. Matters go from bad to worsewhen the Klingons arrive and stake their own claim on Flyspeck. Then another, more deadly power threatens them all, and suddenly Dr. McCoy and the Starship Enterprise find themselves pitted against an alien fleet in a battle they have no hope of winning.
As I read more and more of the old Star Trek books, I have come to realize that anything written by Diane Duane is going to be a winner. This book is no exception. She is able to present the family aspect of the Enterprise crew much better than most. In this story, the command structure is much more apparent than in other stories, due largely in part by the plot device of leaving McCoy in command of the Enterprise. The Doctor handles it well and with good humor. As with Duane's other Star Trek books, linguistics plays a significant role in the story line. I really should read some of her non-commissioned work.