Gordon Freeman has done it, he stopped the striders from reaching White Forest. They were able to launch the rocket and close the superportal, stopping the combine reinforcements. But there was a price to pay for these actions, and that price was Eli's death from the Advisor. Now Gordon and Alyx must make their way to the Borealis, and Gordon is to destroy it. But on their journey, they will meet new creatures, both friends and foes.