The Covenant have invaded Earth and have caused mass panic and destruction in their wake, leaving a group of teenagers stranded on the front lines. They must fight for their lives and survive or die trying to get out of the city.

Alessandra Hirakawa never signed on to fight Aliens, not even when she was a proud memeber of the 105th ODSTs. She preferred to fight an enemy that looked, sounded, and thought like her, so becoming a cop seemed like the perfect retirement choice. However, even small towns on hidden planets aren't safe from an alien foe on a mission to wipe out all that humanity holds dear.

In wartorn Mombasa, thousands of troops and refugees funnel toward an old, rundown hospital in the slums, the last stronghold of a city besieged by an army bent on extermination. Overcrowded and undersupplied, the hospital is not the bastion it needs to be to provide so many people their safety. In what many think are humanity's last days, distrust, fear, and guns rule all.