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.
(..) around the States too weII. He needs a IittIe heIp. Is that a probIem, Tony? No probIem. Good. So what's the big mystery with the BoIivian situation? You gonna teII me what happened with Sosa, or what? A Iot of buIIshit, that's what happened. (..)1983 Scarface