DL4: Dragons of Desolation is a weird one, and wraps up the material novelized as Dragons of Autumn Twilight.  

It is weird because the module provides a massive dwarven city to explore, complete with a novel mapping system of pregenerated “blocks” but then doesn’t populate them with much of any real interest and encourages the DM to get the players through the area quickly. OK. How about doing that by just cutting out the vast city? For a series of modules that was totally comfortable railroading players up to this point, this seems like a really odd choice.

After the dwarven city, the players explore a floating tomb to find the Hammer of Kharas to secure the help of the dwarves, after which they are attacked by Verminaard. Just before he can be defeated, he commits suicide by jumping into a pit to deny the players the satisfaction.

Wait, I don’t remember that happening in Dragons from Autumn Twilight. Or the whole refugees from Pax Tharkas thing from DL3, now that I am thinking about it. That’s because the novel climaxes at Pax Tharkas, with Verminaard unwisely taking on the heroes solo and getting killed in the ensuing beatdown. The reason for the difference: the novel was written after the modules were completed.

Which, fine. But holy crap, why be so strict with the railroading if the modules end at a different place than the novels in the first place?! **flips a table**