It was nearly dark when the three figures crept out of the back entrance to the bank and into the alley.  Silas watched them with interest.  He was holed up in the building across the street.  He barricaded himself and a few coworkers in an empty office when the virus started spreading through the building.  It wasn’t as nice as some of the others, but there was no outward facing glass and the door was solid oak.  It had held for five hours.  They spent that time in silence, just listening to the zombies beat ceaselessly against the door, waiting.

Read from the beginning!