In 1987, Georgia spirals deeper into her obsession with the mysterious Bone Gospel, which she learns is a real book, while in the present day, the investigation into a series of copycat killings leads to the discovery of a podcaster's body.

As the scientists descend into madness and a ritual linked to the signal unfolds in 1987, Georgia and Michael race to find Millie and uncover the truth in 2024 - only to realise the killer they're chasing has been right under their noses all along.