Game of thrones (Season 4, episode 4)

I guess they needed to remind us about the White Walkers. This scene has not been taken from any of the books, like a few other scenes from this episode. The WW’s are hardly mentioned in book 4 or 5, so the mystery surrounding these creatures might not be answered for a few years still (Season 4 of GOT is based upon the 2nd half of book 3).