Hard-working Gavin Shelburne (Barry Bostwick) and his wife Mary (Kim Darby) have two young children and a third one on the way. It is difficult making ends meet but she insists that she needs help with their children as her delivery date nears. He acquiesces even though his family is rapidly becoming a greater burden than he thought it would be.
Mary hires mousy but mature-seeming high school nerd Cinni (Diane Franklin) who seems to be a perfect choice for a babysitter. Cinni is asked to report for work at the beginning of summer. The girl meets Gavin for the first time looking very different than she did when Mary and the kids met her. The hunky dad is immediately smitten and not very subtle in showing it.
The attraction is mutual though he can hardly guess that this teen girl has a highly evolved and profound psychosis that is getting progressively worse. It manifests itself in hostility and a hyperactive libido. Mary was unable to sense any of that in Cinni or the nearly single-minded desire the girl has in stealing Gavin.
As Cinni accompanies the family on vacation to their beach house suspicions and jealousy are kindled within Mary. Gavin has lost interest in his awkward and plain-looking wife not merely because of her pregnancy. Mary doesn't look like she was ever comfortable in herself or her sexuality and Cinni's presence makes her that much more self-conscious.
The lovely Diane Franklin (Another of my boyhood crushes) hams it up as Cinni which is a good thing since every other character is a colossal bore. Kim Darby's character would drive any man out of the house whether or not Diane Franklin's Cinni was waiting for him. If he ends up in the arms of a beautiful psychopathic murderess...Well...A man makes his trade-offs like a woman does but often with different priorities.
This 1983 CBS TV movie has a sleazy exploitation feel and a sense of the familiar. It should. It is very similar in theme to 1980's The Babysitter starring William Shatner and Stephanie Zimbalist as well as a fair number of similarly themed thrillers before and since, better and worse.
It seems like Hollywood somehow has this notion that married women normally view sexual betrayal by the men they love as par for the course while seeing betrayal by a female acquaintance as manifestation of a severe mental disorder.
Hence the villainess is a malevolent and warped young sexpot and the husband character is just a weak and vulnerable schlub - more a victim of seduction than an active participant. Not real sure who that is intended to fool.
