Zach's explanation was too doubtful. But some refugees including Noah chose to believe him.
Although their reasons to believe were different. The refugees believed his story mostly because of their sentiment, as they knew him in the past but Noah chose to believe because it meant they had a chance to fight back the vampires and save the kidnapped refugees.
Zach also said that the vampires didn't treat the kidnapped refugees as food or something. They even would give them some blood in a little cup every day.
He thought that they kidnapped the refugees to transform them to be vampires not to eat them. As for the reason they only kidnapped a few people each time because each transformation needed some time to complete.
Noah then asked him to show the vampires' den. Zach agreed, but he refused to come himself. He said each vampire could restrict and control the vampire's servant to a certain degree when they were near their master.
