From character names to story elements, P.C. and Kristin Casts’ House of Night series is a treasure trove of allusions to Greek mythology. Nyx’s origins are in Greek myth—she appears in Hesiod’s Theogony, Homer’s Illiad, and other ancient Greek texts. Aphrodite takes her name from the Greek goddess. But the references to Greek myth that fascinate me most are those related to Nyx’s Otherworld. The Casts have taken the ancient Greek’s Underworld and added their own imaginative twist, creating a colorful, intriguing new answer to the eternal question, “Where do we go after we die?” Just like the Underworld in Greek mythology, selective visits to the Otherworld by the living are allowed. Also just like the Underworld, some visitors can never leave. And while the two aren’t identical, there are enough similarities that it’s interesting to compare and contrast.

The uncertainty of the afterlife is universal, a timeless question without an answer because all the experts are gone. With the field wide open for conjecture, there are countless myths and stories about life after death. Ancient civilizations across the globe had their own (often eerily similar) explanations for what happens after death, but thanks to rock-star writers like Hesiod and Homer, Greek myths remain the gold standard.

Back in the day, ancient Greeks didn’t think of the Underworld as a bad place. It was simply where people went after they died. But it was still dangerous. Very few living mortals visited the  …