Citadel of Skulls is the second book from the warpstorm trilogy (actually starting with The Frozen Reaches ) which continues on the adventure path for the Rogue Trader system. On the hunt to discover the cause of vanishing settlements and increased xenos sightings, you and your fellow Explorers are thrust on a perilous journey. You discover that a great beast has awakened from beyond the edges of the Koronus Expanse which risks destroying all that is nearby. Before you can attempt to seek it out and destroy it, you have to discover what and where it is. Finding the answer is a almost impossible task, pitting you against an infamous pirate lord blessed by Chaos.
Like a big majority of Fantasy Flight products the module looks asthetically fantastic. Careful proof-reading and design means I haven't spotted a single error within this book. The first few pages give excellent detail for the Games master to get a good feel of what is going on whether they have played the first adventure or not and gives plenty of background information to help them get a good understaning of what the player will be facing. There are maps for the GM to refer to so they have a good visual aid of the area the players will be roaming in and in case, like every adventuring party, they decide that going off course is the only route possible then there is plenty of fluff to help them get it back on track.
The adventure module does recommend that you run The Frozen Reaches first and I do agree. While this could be run as a standalone in itself you would need to help come up with an explanation as to why the players are doing this and Frozen Reaches sets this up really nicely. I personally haven't read the first module of this adventure path but thankfully there is a small description of it at the beginning of this book.
All the NPCs are detailed in the appendix and also help give a bit more insight to them, so as to help the GM act them out if necessary. It has stat blocks for everything and a list of all special abilities or talents. It also has, unsurprisingly, a list of experience you can get for each chapter in the adventure and achievement points the player can earn as well. They could have given far less detail or for less information and you would still be able to run this adventure module successfully and instead you get a fantastic level of information to drip feed your players as they go. I love how some of the NPCs have little quirks that only occur in certain situation that you can choose how they affect your players. For example, Skar's little quirk is just a nice touch to add.
The adventure itself is excellent. Again I don't want to give away too much of the detail surrounding the adventure but it is in the true, gritty style of the 40K universe and one particular line stood out to me that really did sum it up perfectly:
"The explorers should get out by the skin of their teeth"
Overall this is an excellent quality book with plenty of detail and beautiful artwork as would be expected from a Fantasy Flight module. The story is interesting and challenging for the players and in plenty of detail. It really feels it would be much better for the players if you run the first module before going onto this one, however a resourceful Games Master could easily slot this in to their game.