As the transit system is out of service, the player has to go through the previously inaccessible areas in Sector B, the Coolant Reservoir Facility and the attached canal system, to reach an elevator which takes him to the Administration Center in Sector D. The player must travel through the devastated remains of the labs as alien creatures begin to teleport in. Gordon Freeman is told by his science team colleague Eli Vance to head to the surface to make a call for help. As a result of the resonance cascade, a dimensional rift has opened between Earth and the alien world Xen, causing hostile lifeforms to invade the facility. The chapter begins in the ruins of the test chamber after the incident. For the the game's full story, see the Half-Life storyline article.
