Follow Alyx to a lift and listen to what she's got to say.
You'll end up in the control room.
You will be asked to launch it. Get to the console and press the red button.
After half a minute, the rocket will start.
Follow Alyx and her father. You will finally get a chance to talk. You will learn some things about the next episode.
When the conversation is over, follow Alyx and her father outside. Then watch the portal.
Follow Alyx's father inside the building. He will see you off to a chopper.
Suddenly, two creatures will show up. In the cutscene, you will watch how Alyx's father is killed.
You and Alyx will be saved by Dog..