Invitation to Hell (1984) 

When a family moves to a suburban California neighborhood, everything is going great. The neighbors are nice, the neighborhood is clean, and there is a local health spa close to their house that everyone in the town belongs to. At first they consider joining it until their neighbors and co-workers hassle them constantly for not doing it right away. They start to get a little suspicious towards why they are so interested in them joining, but not the point where they think something is wrong. The wife and kids are up for it, but the dad is skeptical and fears a bit of evil in the spa. Is the dad just a little superstitious or is the spa really an Invitation to Hell? - IMDb

 

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