The very title of this adventure is redolent of a pulp classic, and the plotline is filled with jungle outposts and evil cultists and legends from the past...
There are various ideas for how to get the party involved in the adventure, not all of which have anything to do with what they are actually getting themselves into! That's a neat touch as they'll be expecting something quite different. Scaling information, a random monster list, and some background notes are also supplied to help the DM get organised. There is also a rather small map of the tropical island on which the adventure is theoretically located, although any suitable remote jungle area with an extinct volcano in your own campaign world will do.
Quite a lot of the background is information that the party should have little difficulty in discovering once they know they are heading this way, indeed much of it is common knowledge... not, of course, that it's all correct. A vanished mage and attacked caravans ought to be enough to get the party investigating anyway, never mind those rumours of an ancient evil set loose once more...
The actual adventure begins at the base of Mount Icpitl, the extinct volcano, under which, 'tis said, the ancient evil once had its lair. Getting them there is left to you. Once inside the underground complex the delve proceeds apace, with plenty of monsters to fight and puzzles to solve. Many of the puzzles are supported by handouts that let the players see what their characters do, hopefully this will aid them in figuring them out. The second part of the adventure, within the crater of the extinct volcano itself, is quite combat-heavy (and comes with hints for how to reduce that if you so wish). One thing to watch out for is poison. The Bad Guys use it a lot, so expect to see plenty of Fortitude saves. There's quite a good mix of encounters where those encountered might be willing to talk - if approached the right way - and ones where a brawl is going to ensue without the option.
The third and fourth parts involve the exploration of a pyramid in the centre of the extinct volcano. There are plenty of hostiles to fight and some interesting items to, er, liberate. The adventure ends in a swirl of a mad sorceress and a ruthlessly ambitious yuan-ti, who must be defeated, and there's always the question of what to do with the staff bearing a gemstone said to hold the spirit of the original Emerald Cobra... some suggestions here hint at the possibility of continuting the adventure, although you'll have to write that for yourself.
It's an exotic setting, with ancient evils rubbing shoulders with contemporary living lizardfolk and more, combat-heavy but exciting, and with possibilities for further development. A very pulp or Conanesque feel to the whole thing.