This one gets off to a strange start. You will be witnessing a series of ill events, each of which befalls the next person to come into possession of a mysterious star map. That cursed map changes hands often, and in doing so claims many a victim. The map itself is not even readable by any who are unfortunate enough to own it. That remains true until Captain Malcolm Reynolds manages to win it in a card game on an Outer Rim moon. Of course trouble follows anyone who owns the map, and things are no different for Mal once he takes possession; however, he does have an advantage that the previous owners did not. That advantage is River Tam. River claims that the map reveals the location of one of the legendary Arks, ancient generational ships that traveled from Earth-That-Was to the Verse, and carried humanity across the stars with them. Everyone living in the Verse is a descendent of those that came on the those ships and the technology that made it possible no longer exists. That means if River is right then the salvage potential of finding such a ship is enormous. This looks like it could be the big score the crew has been waiting for; however, River isn't telling the entire truth. There is something else waiting at the end of that map, something the Alliance wants kept secret at all costs.

This winds up being a great story that reveals a lot of the history of the Verse while also diving into the events that damaged River's mind and gave her some of the powers that she has been known to exhibit at unpredictable times. River hopes that by finding the power that exists at the map's destination she may be able to figure out what was done to her, but she keeps that information to herself because of the danger it represents. When you combine the crew's hopes for a big payday with a hidden agenda kept secret by River, then you know there will be trouble when this secret destination is reached. And that right there is an understatement. The Firefly crew seems small against the backdrop of an Ark ship and a trip across time or when compared to the Alliance and their twisted plans to create super soldiers, but they do have each other and that is going to have to be enough if they want to survive. 

Although this was published as the fourth book in the series it appears to have been written as the third and experienced publishing delays, so reading this one prior to the actual third book might be a better choice. It also has a different author from the others, which results in a slightly different representation of our beloved characters, but the story itself more than makes up for it. Listening to the audiobook, which has the same narrator as the others, really smooths over the author change and makes for a nice consistent experience.