From the introduction:
The Dune Campaign begins with the characters meeting for the first time on Caladan, brought together by order of Thufir Hawat. He‘s picked them because of their loyalty to the Duke and their special qualifications. They are sent to Arrakis as part of the first wave. There, they coordinate with an Atreides Mentat/Strategist who directs the securing of the imperial city of Arrakeen as well as the PCs‘ activities. They spend part of the first chapter securing the palace at Arrakeen from Harkonnen saboteurs. The Harkonnens left several hundred Agents behind; soldiers waiting for the opportunity to strike, spies posing as House servants, and traps to disable equipment and slaughter Atreides personnel. The characters move from encounter to encounter, using all their skills and abilities to hunt down the Harkonnen resistance. A detailed map of the palace is included.
The rest of the chapter is spent moving from one building/facility to another in Arrakeen, searching for members of the local cell of the Harkonnen Underground. Finally, having gathered enough information to know the Harkonnen cell is operating from a base in the Shield Wall, the characters assault the Wall and ferret out the Harkonnens.
This scenario was partially developed for the Wizards of the Coast version of the game; it subsequently was published on the web by the author in its final - unfinished - state.