There are three that I know of: Razing of Redshore for 20-21, Storm Lord's Keep for 21+, and Quicksilver Hourglass for 30.
Razing of Redshore is probably the one that best accounts for 20th level characters' vast options, but it might be hard to adapt since it's about a fight between an assassin's guild and an epic druid for control of the "source" of epic power. Still, you could change it to revolve around another artifact, although you'd have to alter the backstory. It's also a bit weird to suddenly introduce this super-strong assassin's guild which no-one's ever heard of before, but they are *assassins* after all, so I guess it's not that bad.
Storm Lord's Keep, which is about a storm giant sorcerer's rage at the death of his daughter and the resulting ending of his lineage with dire consequences, probably has the coolest story, but despite some really cool features, it's little more than a scaled-up (no pun intended) dungeon crawl in the skies. By which I mean, a quick-thinking epic group can probably derail it pretty badly. Still, you might be able to take some inspiration from it. If nothing else, the Stormhold is one really cool castle.
Quicksilver Hourglass I know the least about. It's apparently a dungeon-crawl in a demiplane holding a trapped deity. To me it seems fairly gratuitous (a DVR 5 demigod has no place being a dungeon "end boss" to my mind.)
Probably the best option is to make something yourself. If you'll tell me a little about your group and what they've been doing, I can come up with some suggestions.
I do have one idea, kind of a mashup/ joint sequel of Tomb of Horrors and Bastion of Broken Souls, but it needs a little time to mature.