The play begins in front of the palace of Thebes, with Dionysus telling the story of his origin and his reasons for visiting the city. Dionysus explains that he was born prematurely, when Hera made Zeus send down a lightning bolt, killing the pregnant Semele and causing the birth. Some in Thebes, he notes, don't believe this story. In fact, Semele's sisters Autonoe, Agave, and Ino claim it is a lie intended to cover up the fact that Semele became pregnant by some mortal; they say Zeus' lightning was a punishment for the lie.