The real world was far too real to leave neat little hints. It was full of too many things. It wasn’t by eliminating the impossible that you got at the truth, however improbable; it was by the much harder process of eliminating the possibilities. You worked away, patiently asking questions and looking hard at things. You walked and talked, and in your heart you just hoped like hell that some bugger’s nerve’d crack and he’d give himself up.

Terry Pratchett, Feet of clay