This information has to be delivered to White Forest so that the Resistance can use it to shut down the superportal and prevent an even greater Combine invasion. It contains information relating to the location of the Combine Overworld and allows the creation of the superportal to be controlled from the 'other side'. A crucial part of the plot is the transmission packet which the Combine sacrificed the Citadel to send, a copy of which Alyx and Gordon stole before making their escape. Kleiner's broadcast in Episode One, has caused a portal and communications blackout on Earth-stationed Combine forces, leaving them isolated and disorganized.

The destruction of the Citadel, as explained by Dr. Combine Advisor pods have also been scattered throughout the region.

After the destruction of the Citadel, the Combine are working to open a massive superportal to call for reinforcements. Continuing the plot of Half-Life 2 and Episode One, Episode Two consists of seven chapters telling the story of Gordon Freeman and Alyx Vance's journey through the Outlands to a large Resistance base named after the forest. This article describes the Half-Life 2: Episode Two storyline, chapter by chapter.

Half life 2 episode one walk through