Transfiguration

The Transfiguration story is in 3 of the 4 Gospels. It is strangely absent from John. The three that have it tell is that Peter, James and John were there to witness it. If John was there, perhaps he felt he shouldn't have put it in his Gospel. Jesus did say to them not to tell anyone about it until He had ascended to Heaven.

Mark 9: 2-12
Matthew 17: 1-13
Luke 9: 28-36

Mark mentions the line about Elijah coming first, but only Matthew explains that they are talking about John The Baptist. Luke's version isn't much different.

Paulo Coelho's book The Fifth Mountain tells the story of Elijah. He uses artistic licence to give the tale some depth. The last line of the book confirms the belief that ELijah came back as John The Baptist.