There's no 'mystery' (to/as to/about) why we're here. = It's no 'mystery' why we're here. [=we know why we are here]
His success is something of a 'mystery'. = His success is a bit of a 'mystery'.
We'll reveal the identity of today's 'mystery' guest after these commercials.
(..) Bones, even you are capable of a little magic. Which is why I slipped a dollar under Christine's pillow when I kissed her good night. See? A little mystery is good for the soul. What do you have there? Oh, I'm just finishing up some paperwork on the Lenny Jay case. Oh, perfect. (..)2015 TvShow: Bones Title: The Promise in the Palace Season: 11 Episode 7
(..) in her apartment. So maybe he was cooking and... Reached around her neck and killed her. I think we might have found Klarissa's mystery lover. Take a look at this, Victor. What is it? Your fancy truffle oil was on Klarissa's neck. I left that oil (..)2015 TvShow: Bones Title: The Promise in the Palace Season: 11 Episode 7