The opening chapter picks up where Episode One left off. The Citadel Core gave out as Alyx and Gordon were leaving City 17, and the resulting shock wave has derailed the train in which they were traveling. Gordon and Alyx survive the crash, and Alyx retrieves the Gravity Gun in order to free Gordon from the wreck. The ruins of City 17 are visible, with a superportal forming above the collapsed Citadel. A portal storm occurs, appearing to emanate from the Citadel ruins, destroying the damaged rail bridge and opening a path into a mine shaft for Alyx and Gordon to follow.
Alyx informs Gordon that they must contact the White Forest base and deliver their data packet. They travel through a short Zombie and Antlion-infested mine tunnel to a communication building, and Alyx is able to contact White Forest base. Dr. Kleiner and Eli Vance are relieved to learn that Gordon and Alyx survived the detonation of the Citadel, and Dr. Magnusson is introduced as the head of the White Forest base, more concerned with the data packet than the safety of Gordon and Alyx. The sound of a hunter-chopper and an overheard Overwatch message confirm that the Combine are still searching for the duo and the data packet Alyx possesses.
Shortly afterward, Alyx is critically wounded by a Hunter. A Vortigaunt arrives in time to drive off Antlions and stabilize Alyx's condition. Gordon becomes separated from Alyx and the Vortigaunt and must travel through Antlion caves to meet them at a nearby Resistance outpost. It is during this cave journey that Antlion Grubs and Workers are first encountered.
This chapter contains examples of:
- Video Game Vista: At one point, you're required to take a look at the scenery towards the destroyed City 17, an event that prompts a resonance wave that removes a fence and allows you to continue.
