House of Dark Shadows

Willie Loomis, a handyman in the service of the Collins family, searches for old treasures in the family crypt. By chance, he frees Barnaba Collins, a 175-year-old vampire who enslaves him. After his release, Barnaba attacks Daphne Budd, Elizabeth Collins-Stoddard's secretary. She is discovered by Jeff Clark, who takes her back to the house, where Dr. Julia Hoffman provides her with medical care.

Barnaba shows up at the Collins house and introduces himself as a distant relative from England. Elizabeth and the rest of the family immediately take a liking to him. Barnaba insists on moving into an abandoned old house and having a ball in honor of the family.

The night before the ball, Barnabas is bitten by Carolyn Stoddard, Elizabeth's daughter. Later at the ball, he meets the governess of young David Collins and Jeff's girlfriend Maggie Evans and instantly falls in love with her, as she is strikingly similar to his long-dead fiancee Josette du Pre. Maggie thinks about leaving Collingwood, but Barnaba persuades her to stay. Back at the Old House, he tells Willie about Josette, who committed suicide on the night they were supposed to get married. Carolyn overhears and out of jealousy threatens to expose him. An enraged Barnaba, much to Willy's horror, inflicts a fatal bite on Carolyn. Shocked, Willie drives Carolyn home; she slowly walks to the door, but soon her dead body is discovered by Mrs. Johnson's maid.

Carolyn is buried in the Collins family crypt. Dr. Hoffman analyzes Carolyn's blood samples and recognizes traces of the same unknown virus that was found in Daphne Budd's blood. Professor Eliot Stokes, a family friend, tells Julia that the recent attacks in Collinsport may have been carried out by a vampire.

Carolyn rises as a vampire and tries to attack David. Stokes and Julia try to explain their vampire theory to the family members, but Elizabeth and Roger refuse to listen. Carolyn attacks her ex-fiance Todd and bites him. After he is brought to Collingwood, the family realizes that Stokes and Julia were right about the vampires. Todd searches for Carolyn again, but the rest of the family use him as bait, corner her and stake her, after which she instantly dies.

Julia discovers that the cause of the dark events is the vampire Barnaba. She visits him in the Old House and convinces him that she can use her scientific knowledge to make him human again, and he reluctantly agrees. Julia gives him injections, which soon allow him to walk in daylight. Barnaba and Maggie start spending time together while Jeff is away in Boston. Stokes argues with Julia about whether Barnaba can be helped, realizes that she is in love with him, and reminds her that the vampire himself loves Maggie. Overcome with jealousy, Julia gives Barnaba an injection, from which he begins to age rapidly. In a rage, he kills Julia. A terrified Maggie, who witnessed the murder, tries to escape, but Barnaba catches her and bites her, after which she vows to come back for her. Jeff returns from Boston, Stokes and Roger tell him the story of the family and warn him that Barnaba intends to make Maggie his bride. That night Barnaba bites Maggie again, whose blood rejuvenates him, and then kidnaps her.

Jeff and the others chase them, resulting in Roger and Stokes being killed. Jeff eventually finds Maggie in an old church in a trance, wearing Josette's wedding dress. Willie warns him against trying to stop Barnaba, and when his warnings don't work, knocks him out. Willie takes Maggie out of her room and into the chapel, where Barnaba is waiting for her. He puts her on the altar and is about to bite her. Jeff wakes up and shoots him with a crossbow, but Willie is in the way of the arrow, running to stop Barnaba. He lures Jeff out of hiding, puts him into a trance and forces him to be a witness to the wedding. When Barnaba tries to bite Maggie again, he suddenly starts screaming in pain: Willie hits him in the back with a crossbow bolt. Barnaba strangles the mortally wounded Willie, but Loomis' attack snaps Jeff out of his trance long enough for him to drive the bolt deeper into the vampire's back and eventually pierce through him. Jeff rescues the revived Maggie, after taking a look at the bodies of the supposedly dead vampire and Willie Loomis, after which they leave the destroyed chapel together.

In the scene after the credits, Barnaba's body turns into a bat, which quickly flies off the screen.