is rotten in Denmark
something is rotten in (the state of) Denmark
Something strange or suspicious is going on. The line comes from Shakespeare's Hamlet. Why is Katherine being so nice to me all of a sudden? I'm telling you, something is rotten in the state of Denmark. "Something's rotten in Denmark," the detective muttered as he looked through the surveillance photos.
something is rotten in (the state of) Denmark.
Prov. something suspicious is going on. (From shakespeare's play Hamlet.) Jim: Look, there's a light on in the office, even though it's way past the time everyone should have left. John: Something is rotten in the state of Denmark. Jane: I wonder why Fred is coming in so late every morning. Jane: Something is rotten in Denmark.