Joanna Chase's return to Rustling Willows Ranch in Montana is compelled by eerie and mysterious calls from a past she scarcely remembers. Dean Koontz's novel, 'The Big Dark Sky,' unravels an intense tapestry where a misfit ensemble, bound together under Montana's immense firmament, confronts an invisible menace threading their fates. Amidst haunting memories and a terror-stricken community, they stumble upon a madman's apocalyptic design. The group's interlaced destinies hinge on thwarting a looming cataclysm set to erase humanity, making their unforeseen alliance mankind's last bastion against the shadows encroaching under the Big Dark Sky.