http://wccftech.com/writer-marc-laidlaw-episode-3-plot/

Half-Life 2 Episode 3 will most likely never happen. That’s a sad reality fans of the franchise have come to accept by now. However, writer Marc Laidlaw (who departed Valve in January 2016) suddenly decided that they should at least know about the plot.

He posted the entirety of the Episode 3 story on his official website. The site is now inaccessible, probably due to high traffic, but we’ve posted it in its entirety below, with all the names corrected.