Set one year after the events of Hell House LLC II, the hotel is on the verge of being torn down when it is purchased by billionaire Russell Wynn as the new home for his popular interactive show, Insomnia. He invites journalist Venessa Sheppard and her crew to record everything happening inside the hotel leading up to the performance - but they soon encounter a more nefarious plot, one that threatens to unleash a veritable hell on earth.

A deadly pathogen is unleashed and unknowingly carried to Dana Overbeck's 30th birthday party, where her estranged father, Rufus, is coming to make amends.

A scheming con artist poses as the innocent babysitter "Amber" to steal from a wealthy occult enthusiast with a reclusive son, Kevin. Her crew arrives to clean out the house just as Kevin stumbles upon a prized artifact and unwittingly summons a trio of witches known as The Three Mothers.