Now that's a straightforward task: just go kill a dragon that has not only been mortally wounded but they've even tracked down its lair for you... or is it? Apart from the usual unease the thought of a cornered wounded predator ought to arouse, there are of course other issues for the party to deal with!
Putting both the 'dungeon' and the 'dragon' into Dungeons and Dragons, this is a delve with a difference... just about everyone around reveres the dragon in question! The background material for the DM lays this out, and provides useful material like scaling advice should your party be stronger or weaker than the recommended 40 character levels, bearing in mind that it's supposed to be challenging in places, and sometimes the best option will be to retreat and regroup. Remember, you don't have to outrun the dragon, merely outrun the slowest party member! This is intended to be combat-heavy, but many of the opponents are well-developed NPCs rather than hordes of cookie-cutter monsters, which makes it all a bit more interesting... but also necessary to study them before the game so as to run them to best effect. Likewise, review the maps as it's easy for parties to get lost, especially if they are not meticulous mappers.
There's sufficient backstory to explain what's going on, then the action proper starts with the party standing outside the injured dragon's lair ready to go in. There are four levels to the complex and all have inhabitants with good reason to be there... and none of whom are welcoming to visitors. Loads of notes are provided to help make the action more vivid and entertaining - several encounters even have a whole section called 'Cool ways to make this fight interesting' associated with them!
The whole thing is replete with little side-notes that make each and every encounter unique and distinctive. Oh, and there are traps to avoid as well as monsters to fight. Stat blocks and descriptions are placed just where you'll need them and there are a few illustrations you can show the players and handouts that you can give them. And of course, finally there's a big cavern with a massive heap of shiny treasure and a dragon on top. Classic stuff, an adventure that is as fun to run as it is to play, and one thoroughly recommended.