colonel mustard with the candlestick in the parlor! 
the word clue has its origins in some greek mythology! remember theseus and the labyrinth? he went in there to find the minotaur, but daedalus told him he should make sure to get out again, so bring a spool of thread so he can find his way.
that spool of thread? it’s called a clew. hence, clue!