From the back of the book:
Old Soldiers Never Die
What begins as a simple expedition to settle a new village in the ruins of the mysterious Castle Inverness sets off a chain of events that could threaten every living being from Winterhaven to Hammerfast. Not everyone in the Nentir Vale is happy yo see civilization brought to Inverness, particularly the ghost of Salazar Vladistone, who commands the spectral legion called the Phantom Brigade.
March of the Phantom Brigade is an adventure designed for the Dungeons & Dragons Encounters official play program. It includes information the Dungeon Master needs to run the adventure, 13 ready-to-play encounters (each intended for one session of play), and full-color foldout battle maps depicting the various encounter locations.