Well, this is 'Dungeons and DRAGONS' after all, so it's nice to have an adventure that involves a dragon occasionally. It involves a crafty old white dragon by the name of Charasta, and the background notes for the DM tell you all about her.
There are various ways you can introduce this adventure into your campaign. Perhaps they hear rumours of a dragon in the area and go looking, or they may be on the trail of an ancient box that is said to have the power to alter the weather. More likely they are investigating some caverns and they come across her lair by chance - she's kept it well-hidden, after all.
Whatever you choose, the adventure involves a visit to her subterranean lair. This will prove a challenge as it is freezing cold and mostly underwater! Copious notes are provided to enable you to handle the effects of cold and being submerged on the characters. The map is based on one by Dennis Kauth that originally appeared in the Map of the Week feature on the Wizards of the Coast website, but the original wasn't bigger than the one in the module, despite suggestions that you download it (which now takes considerable searching to find anyway!).
There's a comprehensive description of the lair itself, and plenty of detail about how Charasta will respond to the party coming to visit... it doesn't appear that she'll make them welcome, and in fact the only option appears to be to fight - both with her and the various guardians she has in place (along with assorted barriers and traps for the unwary). The party will have to be cunning, skillful and lucky to avoid a frigid demise...