Semele was, according to some versions of the story, a priestess of Zeus. As per usual, Zeus’s wife Hera was mad at him for cheating, and took it out on the woman. In Semele’s case, she planted doubt in Semele’s mind that her lover truly was Zeus, which led to Semele demanding that Zeus show himself to her in all his divine glory. Unfortunately, mortals cannot survive such a display of godly power, and Semele was incinerated by Zeus’s radiance.
But the child she bore was saved by Zeus, who sewed the fetus into his thigh and carried it to term. The infant would become the god Dionysus, who would rescue his mother’s shade from Hades when he grew up, and bring her to Olympus, where she too would become a god.