Skilfully mixing real-world history with the background of the Deus Vult campaign setting, this is the story of Rouen: trading centre and capital of Normandy, visited from Scandinavian lands as well as from Europe... and with strongholds of the Order as well. Based there or just visiting, there's plenty of atmospheric detail to allow the city to come to life for your players.
History, citizens, their amusements, the appearance of the city and the locations within it - they're all here, painted vividly and atmospherically. Naturally the cathedral is described in detail, complete with sufficient material to allow you to describe services even if you are not familiar with the mediaeval Mass. At every turn are notes which can be used to provide incidental events that heighten the role-play and give the feeling of really being there.
Of course, as well as the regular merchants, clerics, nobles and everyday working folk, there are others. An occultist hidden away here, the Order's Preceptory there... and a thriving Jewish community, not to mention a trapped demon. The practice of Medicine - as a science divorced from clerical healing that is - is in its infancy, but there is at least one noted Doctor in town, with some fascinating notes on early medicine and the advice given to doctors in how to conduct themselves.
If you have not already had quite a few ideas, there's a whole chapter of encounters to use when the party is in Rouen. Some will provide but passing diversion, others are good for a side-adventure if not a whole scenario in their own right should you so wish. Several important citizens are provided in full detail, including stat blocks - allies, patrons, enemies, chance encounters: again, whatever suits the needs of your plot or party actions. There is also a Bestiary section with an array of new creatures to introduce into the mix.
Finally, there are a couple of adventures in and around Rouen that you may wish to run. Both provide plenty of interest and excitement, with investigation as well as combat required to resolve them.
The one thing that's lacking is a map of the city, although there's a sketch map of the surrounding area in one of the adventures. That lack and the odd typo a good proof-read ought to have caught are the only flaws in a fine city to add to the alternate history that is Deus Vult.