A well-known novelist team, Alex and Clair Jenkins wrote primarily gothic novels; their biggest success, The Ghost of Corinth Point, was even being made into a major motion picture. It was late 1970 or early 1971 that they received an offer from their best friend, artist Quentin Collins: he had inherited his family estate in Collinsport, Maine, and did they want to move in to one of the smaller houses on the grounds? Faced with the prospect of living close to their friends, and rent-free at that, the Jenkinses picked their belongings, including an abstract eye painting Quentin had given them, and headed for Collinwood.
Arriving well ahead of their friends, Alex made a great first impression (NOT!) on housekeeper Carlotta Drake by asking of the house was haunted. Though she said it wasn't, Alex ran into a man at the Blue Whale who told him a beautiful servant girl roamed the halls of the great house. Moving into a cottage on the grounds, the couple started work on a new gothic novel, unaware that they would soon be caught up in a story to rival any of their books.
It was about two weeks later that Quentin and his wife Tracy finally arrived at Collinwood. Clair saw Quentin wandering around the old cemetery, and took him back to the cottage to catch up. That night at dinner, Quentin privately confessed to Alex that he was having strange daydreams. Neither of them thought much of it, but Alex would learn that a little knowledge could be a dangerous thing. For the next day while Alex was out riding, he spotted a ghostly white figure going into the abandoned greenhouse. He went in to investigate, and the remaining glass panels in the roof shattered. He was barely able to get out of the way in time. Just after his brush with death, Tracy found him, and told him that Quentin had almost killed handyman Gerard Styles the night before (though she omitted the fact that he had almost killed her as well).
As Quentin's behavior became stranger over the next few days, Alex and Clair became convinced it had something to do with painter Charles Collins and his lover Angelique, who had lived at Collinwood in 1810. Using a trip to New York to consult with an expert on nineteenth-century American art, they found a portrait of Charles - and he was the spitting image of Quentin, except for a scar on his left cheek. They knew then that something supernatural was going on, and brought the portrait back to Collinwood. But arriving late, they decided to wait until morning to talk to Quentin. It was almost a fatal error, for the ghostly Angelique, determined to get back her Charles, wrapped the sleeping Alex in a deadly white mist. Only Clair's quick thinking saved her husband's life.
But they now knew they had to get away from Collinwood as soon as possible. Going to speak with Quentin in spite of the late hour, they spotted him coming out of the old pool house. Trying to discover why he was there in the middle of the night, they found Tracy face down in the swimming pool, unconscious. Able to revive her, Clair took her back to their place to recuperate. Alex went to the great house to confront Quentin, not knowing that the personality of the evil Charles has taken over his friend. Unable to raise his concern for Tracy over Charles' influence, Alex left in disgust. On his way back to the cottage, he was run off the road by Gerard, whom Angelique had sent to kill Tracy and the Jenkinses. Luckily, he survived the crash since Gerard had plans of his own, and he sat exhausted and wounded by the side of the road until Quentin came along. Realizing he was back to his old self, Alex sent him after the murderous Gerard.
Meanwhile, Clair had gotten Tracy dry clothes and warmed her up. Hearing noises outside, Clair took a gun and investigated. When Gerard peered in the window, she shot him in the face. Sure she had hit him, Clair took Tracy outside to see if Gerard was dead; unfortunately, he wasn't. Clair was helpless as he kidnapped the hapless Tracy. It was only later when Quentin returned, having saved Tracy and killed Gerard that the couple learned the whole story of Charles and Angelique, and what was happening at Collinwood now. In an attempt to put the spirits at rest, Alex and Clair joined in a seance. But Carlotta disrupted the ritual, and Alex chased her to the top of the tower, only to watch as she hurled herself to her death.
The end of Carlotta apparently freed Collinwood of Angelique's spirit, much to Alex's relief. (He was afraid it was Quentin keeping the ghost alive.) Quentin put the estate up for sale, and they all packed up to leave. Alex and Clair drove off, thinking their friends were right behind them. But Quentin had gone back into Collinwood to get his canvases and became Charles again. So as the couple drove down the Maine turnpike, their car filled with thick white smoke. Losing control of the car, both Alex and Clair died in the resulting crash.
