Temple of Shifting Sands

From the introduction:

This dungeon can be can be easily customized to a party of any size or level, or run as a level 5 adventure for 5 players. It can work as a small side adventure in an existing campaign, as a standalone one-shot, or the start of a new adventure. Use the links to the tools in their relevant section to customize the adventure to your party.

You can use the dungeon in your campaign at any spot in which you'd need a dungeon. It can slot easily into any setting or storyline. If you need a hook, it could be that a drought is spreading out from the temple, turning everything into sand. The PCs need to investigate the temple and stop its magic before it destroys nearby cities.