After winning a key military victory, Gordon and Alyx are preparing to hunt down a long-lost research ship called the Borealis, and Eli has hinted at some new information about the mysterious G-Man, who placed Gordon in stasis and saved Alyx’s life as a child. He’s met up with the anti-Combine Resistance, including an old colleague named Eli Vance and his daughter Alyx.
Gordon Freeman (who accidentally opened an inter-dimensional portal in Half-Life) has reawakened from a 20-year stasis to find Earth conquered by the alien Combine. Half-Life 2: Episode Two ends with a cliffhanger.