Revenge of the Stepford Wives (1980)

A TV reporter arrives in Stepford to do a story on the American town with the lowest crime and divorce rates and the tightest real-estate market (no one ever leaves). She needs an assistant, and after interviewing the seemingly-plastic women of Stepford, jumps at the chance to hire the down-to-earth Megan, who's married to a newly-hired cop who hasn't yet moved into the town. Four times a day a siren sounds and every woman in town takes a pill (they each claim it's a thyroid condition). Accidents start to happen, Megan disappears for a couple of days, and the reporter realizes something is amiss. When Megan returns as a full-fledged Stepford wife, it's time for action.