Almost a full year has passed since Valve released Half-Life 2: Episode One, the first of three promised episodes that will continue the saga of the blockbuster first-person shooter franchise. Episode Two was originally scheduled for release late last year, but Valve pushed the release date back to later this year. When it does arrive, it will feature not only the continuing story of series protagonist Gordon Freeman and partner Alyx Vance battling the alien Combine, but also the multiplayer action game Team Fortress 2 and a 3D puzzle game called Portal. To learn more about what's going on in Episode Two, we caught up with Valve project manager Erik Johnson. A warning to those who haven't played Episode One yet, as this preview contains spoilers to major events.