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.
(..) But you drove a hot rod, Hodgins? No, I did not. The lemon he sold me broke down after a week. Body parts in park, mystery needs solving. The nest was made by Corvus brachyrhynchos the American Crow. A crow will seldom stray more than miles from its nest. There's a spectacular copse (..)2008 TvShow: Bones Title: The Finger in the Nest Season: 4 Episode 3