Charles Brady and his mother Mary are Sleepwalkers—nomadic, shapeshifting energy vampires who feed off the lifeforce of virgin women. Though they normally maintain a human form, they can transform (partially or fully) into human-sized bipedal werecats (presumably their natural form) at will. They are considerably more resilient than humans and have powers of both telekinesis and illusion. Their one weakness is cats, who are not only able to see through their illusions but whose claws are capable of inflicting severe to fatal wounds upon them. It is revealed that they also maintain an incestuous relationship.
Charles and Mary have taken up residence in a small Indiana town, having recently fled Bodega Bay, California (where they used the aliases Martha and Carl Brodie) after draining and killing a young girl there. Charles attends the local high school, and there he meets Tanya Robertson in his creative writing class. Charles feigns romantic interest in Tanya in order to take her lifeforce for both himself and his mother, who is starving.
Tanya does not suspect the real reason Charles is interested in her. At first, it seems that Charles has genuinely fallen in love with Tanya (to the dismay of his jealous mother). On their first date, however, at a picnic at the nearby cemetery, Charles attempts to drain her lifeforce while kissing her. Tanya tries frantically to ward off Charles by bashing his head with her camera, scratching his face, and ultimately plunging a corkscrew into his left eye; though nothing she does seems to cause Charles more than temporary discomfort.
As this happens, Deputy Sheriff Andy Simpson (who had earlier tried to pull Charles over for speeding and seemingly trying to run down a young school girl while passing a stopped school bus) drives by the cemetery and notices Charles’ (now undisguised) car. When Tanya flees to him for help, Charles attacks Simpson and kills him. When Charles then turns to resume feeding off of Tanya, the deputy’s cat, Clovis, rises to the occasion and violently scratches him in the face and chest. Mortally wounded, Charles staggers back home to his mother who is able to make both of them "dim", i.e. turn themselves invisible, and thus keep Charles from being arrested when the police storm their house. Ominously, a small number of cats begin to gather outside their house.
Knowing that the only way for her dying son to survive is to feed, Mary attacks the Robertson household, killing several deputies and state troopers and severely wounding Tanya’s parents. She kidnaps Tanya and takes her back to her house. Charles is near death, but Mary revives him, and Charles makes a final attempt to drain Tanya’s life force. However, Tanya plunges her fingers into his eyes, killing him. Tanya manages to escape with the help of the sheriff who is later impaled by Mary on the picket fence surrounding the house. The now large number of cats that have been gathering around their house throughout the movie, led by Clovis, all jump on Mary and claw her in a violent attack until she bursts into flames. As she dies, she screams that Tanya "killed her only son". The movie ends with Mary lying ablaze on her driveway and Tanya hugging Clovis, as her savior.Brian Krause as Charles Brady
Alice Krige as Mary Brady
Mädchen Amick as Tanya Robertson
Lyman Ward as Donald Robertson
Cindy Pickett as Helen Robertson
Ron Perlman as Captain Soames
Jim Haynie as Sheriff Ira
Dan Martin as Andy Simpson
Lucy Boryer as Jeanette
Glenn Shadix as Mr. Fallows
Sparks as Clovis
Stephen King as Cemetery Caretaker
John Landis as Lab Technician
Joe Dante as Lab Assistant
Clive Barker as Forensic Tech
Tobe Hooper as Forensic Tech
Mark Hamill as Lt. Jennings (uncredited)
The original music score was composed by Nicholas Pike.
CD track listing: (Side 2 of the cassette begins at track 9)1: Santo & Johnny – Sleepwalk 2:23
2: Nicholas Pike – Main Titles 2:06
3: Nicholas Pike – Cop Kabob 2:25
4: Nicholas Pike – This Is Homeland 4:06
5: Nicholas Pike – Is This What You Had In Mind? 2:49
6: Nicholas Pike – Let's Go Upstairs 2:46
7: Nicholas Pike – You Didn't Get It 3:05
8: Nicholas Pike – Run To That Jungle Beat 2:24
9: The Contours – Do You Love Me 3:00
10: Nicholas Pike – Am I Beautiful? 1:31
11: Nicholas Pike – Let The Cats Run 4:31
12: Nicholas Pike – I'm Going To Make Us Dim 2:36
13: Nicholas Pike – Fly On The Chicken 2:57
14: Nicholas Pike – Impaling Doom 3:44
15: Nicholas Pike – Speedster 3:39
16: Enya – Boadicea 3:30
In Horror Films FAQ: All That's Left to Know About Slashers, Vampires, Zombies, Aliens, and More, John Kenneth Muir praised the first half of the film stating "Sleepwalkers starts out in fine form, as a serious, grim, involving horror film about the last two survivors of a species doing what they must to survive, Krige is incredibly sensual as the half-crazed mother who must be "fed" through the act of sexual intercourse with her son." He then says that the later half of the film "devolves into a campy disaster..." On Rotten Tomatoes the film has a rating of 15% based on 13 reviews, giving it an average rating of 4.2/10.