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.
(..) Neanderthals developed tools o/~ o/~ We built the Wall o/~ o/~ We built the pyramid so/~ o/~ Math, Science, History, unraveling the mystery o/~ o/~ That all started with a big bang o/~ Her apartment's on the fourth floor but the elevator's broken, so... You're just gonna be done? Okay. Cool. Thanks (..)2007 TvShow: The Big Bang Theory Title: The Big Bran Hypothesis Season: 1 Episode 2