"Sure do. Through the tunnel, wipe out whatever manhacks show up, and then out to where 280 used to run aboveground. We got some reports that the Combine'd ceded the central section of the highway to the headcrabs, so we wanna make sure and wipe the whole thing as clean of zombies as we can."

As they make their way into the darkness, in the distance, something hums. An alert eye might well catch sight of first one, then two, then several glimmering red lights.