Brimstone and Treacle (1982)

An evil grifter who might be the Devil (Sting) latches onto the suburban Bates family, Tom and Norma (Denholm Elliot and a woman I could have sworn was a tarted-down Mollie Sugden from Are You Being Served? but who is actually Joan Plowright from .... well, says here she was in Demi Moore's version of The Scarlet Letter (1995) so it's no wonder I'd blocked her out). Sting's emergent goal is to get his pedo-hands on the Bates' invalid daughter, Patricia, in a near-vegetative state since a car accident years before. To this end he pretends to be her former fiance, offers to care for her while Tom works and Norma gets her hair done. This cloying and sketchy new normal doesn't last long; Sting's abuses of the catatonic Patricia become more flagrant, and vile secrets begin seeping out of the wallpaper ... somewhat literally. Framing device and light exposition aside, most of the action takes place inside the cramped Bates Family Manor, revealing the material's source as a teleplay; flat production amplifies the low-budget quirk. Mostly remembered for the contemporary soundtrack (a couple hits from the Go-Gos and Squeeze, a cache of mood music from The Police). Sting went on to wear flying underpants in David Lynch's adaption of Dune (1984).