The Casting of Frank Stone is set during the summer of 1980 in the town of Cedar Hills, Oregon, and involves four young aspiring filmmakers who want to make a horror movie in a condemned steel mill.

Behaviour Interactive's Senior Copywriting Team Lead, Justin Fragapane adds "every decision you make pens the script – and may be the only thing standing between life and death for this group of young friends".

The game has multiple playable characters which include Linda Castle (Lucy Griffiths), a young aspiring filmmaker from Cedar Hills, along with her best friend Jaime Rivera (Andrew Wheildon-Dennis) and his girlfriend Christine "Chris" Gordon (Rebecca LaChance).

They find evidence of high-tech machinery, numerous grim artifacts from history and fiction, and literature related to Frank Stone.

They also learn how each of them got their film strips, with Madison inheriting hers from her mother Bonnie (Bermudez) who Linda once knew back in Cedar Hills, and Stan getting his from a "Robbie G." who is now dead.

They head into town to fix the camera, meeting Sam's son Robert (Idris Debrand) who says he can get them back in the mill, and eventually get a replacement from a mysterious shopkeeper of a curiosities store.

At that moment, the energy surges through the mill and the undead form of Frank Stone manifests before them, unable to be seen visibly without the camera.

Chris is suddenly dragged into a portal that opens nearby and disappears while Frank hunts the rest of the crew through the mill, possibly killing Jaime.

She manipulated a psychologically vulnerable Frank Stone in the early 1960s to commit his murders in the service of a ritual that would summon the Entity, but Sam's efforts thwarted it.

She then began to use the horologium and alternate versions of herself from different timelines to finish the ritual, gifting the camera to the Murder Mill crew under the guise of the shopkeeper.

She then began to collect all the potential versions of Murder Mill that held the strong essence of Frank Stone in order to resurrect him.

With the film now complete, Frank Stone emerges from the projection as an inhuman monster who devours and absorbs either Stan if he has survived up to this point, or one of the remaining group.

In a post-credits scene, the horologium inside the manor activates and an alternate Augustine emerges to meet with the older version of herself in a black cloak.