This is basically the premise of Blackstaff Tower. If you don't want to purchase the novel, you can get a sample for free from Amazon.
Didn't all of the books in the Waterdeep series take place well after the Spellplague?
I think I only read the first one of the series, and it was shortly after publication so it's all quite a bit hazy now... but you might find some non-5e-but-mostly-modern details in those novels
Edit: Amazon link for Blackstaff Tower - first in the series