smoke-filled room从字面上意思是“烟雾缭绕的房间”，引申为“密室；密谈室”。

【例句】
The deal was cut in a smoke-filled room.
这笔交易是在密谈室里敲定的。

We're not going to see a return to the smoke-filled room, in which a few ministers and company bosses made all the decisions.
我们不会再看到回到密谈室，在那里，几个部长和公司老板做了所有的决定。