Forward Watch, Alpha Camp

Talking to Sergeant Mika Horn inside Alpha Camp in the Quarantine Zone will start this quest.

You are sent to take over from a guard whilst he takes his break, you will have to warn the camp of any mass attacks that take place, although none have happened for many hours.

You will have to wait for a long time before anything happens. This time could be used productively to kill undead with a rifle for the slayer collection.