SOLVED. Girl moved to exclusive apartment and solves mystery about millionaire [s]

[Paula]

Written in the last 10 years, I think. Millionaire in nearby mansion places an exclusive group of people in a condo with a Chinese restaurant in it. The millionaire was supposed to be dead but they saw smoke coming out of the chimney. Partners get a set of clues and the girl finds out the millionaire is the doorman and ends up as his protege. There's a condo/building on the cover.

[Donna]

Well it's a little older than 10 years, but that's definitely The Westing Game.

[Paula]

Thanks!

[Kagama-the Literaturevixen]

Rich people... lol

[Emma]

The Tattooed Potato by the same author, Ellen Raskin, is less known and really brilliant.