From the introduction:
Looking at the 4th Edition adventure series H1 Keep on the Shadowfell, H2 Thunderspire Labyrinths, and H3 Pyramid of Shadows – there is very little in the plotline that really ties these adventures together into a full story.
When I read the Keep on the Shadowfell I had hoped that Wizards of the Coast would tie this story together around a growing threat from the Demon Lord Orcus (appearing in H1) trying to spread undeath from the new cool Shadowfell plane defined in 4th Edition. Lot of expectation had been built up around demons, demon lords and the Shadowfell in the Worlds and Monsters publication previously. Sadly my hopes was not fulfilled when I read the Thunderspire Labyrinth and then later the Pyramid of Shadow.
I therefore decided to try to bridge this gap myself, with a conversion guide, doing some changes in the story, background and some of the encounters and images, in order to create an atmosphere foreboding the return of the undead legions of Orcus.
Please note that you should read through the H1 and H2 Conversion Guides first, as it gives you the full background story to the campaign.
This Guide will only take you through the changes of H3: Pyramid of Shadows.