Scenario 1: It is the aftermath of the outbreak and you think you are the sole survivor of your city and there is no hope of escape and one day you got cornered by a hord of zombies but before the zombies could get at you, you are rescued by a unknown person 

Scenario 2: It is the beginning of the apocalypse and no one yet knows about the infection. You have just arrived from a different country/city to visit your cousin but little to your knowledge you would soon be fighting for your life 

Scenario 3: Make up your own