Given the task definition and input, reply with output. In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.

Sentence1: Sandra's son got really excited when he saw fireflies in a movie. Sentence2: He didn't believe that there are insects that really light up. Sentence3: She explained that they are more common out in the country. Sentence4: They decided to take a little drive to find some. Sentence5: His eyes grew wide at the first one he spotted.
Sandra's son, Sandra