WARNING: If you don't want to know what happened in last Sunday's episode (or possibly key events still to come in the books) then turn back now!

For the first time since the beginning of the series, people who had read the 'Game of Thrones' book series were as surprised as people who had just seen the HBO show.

Last night's episode, "Oathkeeper" dealt with many storylines — like Jaime giving Brianne a new sword — that would be familiar to anyone who had read the third book, "A Storm of Swords."

However, the ending of the episode wasn't familiar to anyone because it hasn't even happened yet in the novels.

The final scene starts as a single White Walker (possibly the same we saw at the end of the season 2) takes a sacrificial child from Craster's Keep to an ice castle beyond the wall.

The White Walker then places the child on a frozen alter in the middle of the snow.


Then another White Walker approaches the child.

This is one we haven't seen yet who looks he's wearing a crown made of ice. 

He picks up the child, touches its cheek and this happens:

This is a huge reveal because it showed that we now (partially) know the origin of the mysterious White Walkers. 

It also introduced us to a new character possibly called the Night's King.

Fans of the books were as confused as anyone watching the show.

Was any of that episode actually in the books? #GameOfThrones

— Daniel Burden (@Danburden1138) April 28, 2014

I've read every single Game of Thrones book and my mind was still blown from that last episode #GameOfThrones #WhiteWalkers

— Josh Dolecki (@DoleckiJosh) April 28, 2014

Well, that's certainly something we haven't gotten to in the book. #GameOfThrones #WhiteWalkers

— Jodi Matovich (@JodiMat) April 28, 2014

With two books still left to be published in author George R.R. Martin's series, the HBO show is starting to move ahead of the plot of the books — at least with the White Walkers.

However, according to Vanity Fair, it makes sense because creators David Benioff and D.B. Weiss sat down with Martin last year and know where the story is ultimately heading.

"If you know the ending, then you can lay the groundwork for it. And so we want to know how everything ends. We want to be able to set things up," Benioff told Vanity Fair.

Last night's episode shows that Benioff and Weiss are now ready to start planting the seeds of the series' end-game. However, what last night's revelation means for the overall plot of "Game of Thrones" is anyone's guess because for the first time both reader and watcher alike are all on the same page.

See Also:

'The Following' Villain Is Based On Real-Life Serial KillersAll Of The News Stories John Oliver Mocked In His HBO Show PremiereJohn Oliver Says Goodbye On 'The Daily Show' By Proclaiming HBO Is Way Better'Game Of Thrones' Author George R.R. Martin Explains How A 'Spontaneous Vision' Led To The SeriesAaron Sorkin Apologizes To Fans For 'The Newsroom'

SEE ALSO: 'Game Of Thrones' Author George R.R. Martin Explains How A 'Spontaneous Vision' Led To The Series