Distraught, confused, and half-wild with fear, Sarah Carter emerges alone from the Appalachian cave system where she encountered unspeakable terrors. Unable to plausibly explain to the authorities what happened - or why she's covered in her friends' blood - Sarah is forced back to the subterranean depths to help locate her five missing companions.

Set in the fictional Midlands town of Letherbridge, defined as being close to the city of Birmingham, this soap opera follows the staff and families of a doctor's surgery.