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.
(..) Yes, he fucking has! '..Which contained a statement 'This grim development comes just Jesus! Unless I'm mistaken, our mystery man specified no visual trickery in his original demand, didn't he? I considered it necessary... FUCKING HELL! Mike...! (..)2011 TvShow: Black Mirror Title: The National Anthem Season: 1 Episode 1