Throw this adventure in sometime that the party is taking a long sea voyage... it's easy to drop it into any campaign as it is based on a remote and rarely-visited island. The DM's Background explains the situation in which the party will find themselves and provides a neat way for them to hear at least a little of this information: the captain of the ship they are on likes telling tales of an evening!
It all begins with a shipwreck. The characters wake up on what appears to be a remote and deserted island. This survival situation turns into a delve as a long-lost pirate lair is discovered and (presumably) explored. The pirate captain was a bit paranoid, so it's quite well defended, not to mention other creatures that have moved in. There's a clear plan of the lair, presented as a side elevation (it makes more sense that way, but is nicely-done) and each location therein is described in detail, with what (and who) is to be found there and all you need to run the ensuing combat. And combat there will be, nothing there is going to be interested in a chat.
This is a tough adventure: the traps are complex and deadly and so are the inhabitants. Survivors will find a rich hoard... but they still have to figure out how to get someplace that they can enjoy their new-found wealth. Suggestions for further adventures are included, all-in-all this is a nice little side-adventure to catch your players with when they are thinking about the reason they originally undertook that fateful sea voyage.