Expertly directed by Alan Bridges, also responsible for the satisfyingly low-key and effective Brit sci-fi movie "Invasion" of the same year as well as more prestigious dramas later, this instalment of Out Of The Unknown is among the best of the series that I've seen so far. The depth of atmosphere and mood it evokes belies its modest video-taped production. Beyond Bridges direction, this mood is attributable to Richard O'Callaghan's sensitive and extremely eerie portrayal of the mutant boy. His emphatic but quietly spoken instructions to his hapless "victims" compelling them to his telepathic will provide several genuinely unnerving moments (the bathtub sequence is quite brilliant).
Along with a supporting cast who all take their parts gratifyingly seriously, further atmosphere is provided by good lighting (especially for video of the period) and some very cannily chosen electronic music cues.
Stranger In The Family is not without flaws, however. A sub-plot involving a desperate actress and her pimping agent doesn't really work. Although important to the story (providing both a sexual angle and a more interesting but ultimately under-developed dig at advertising), it feels unequal to it because of their somewhat clichéd characterisation. Also, the bare fact is that writer David Campton has obviously and rather blatantly "borrowed" huge chunks of ideas, plot-points and even dialogue from "Children Of The Damned" (sequel to "Village Of The Damned") made a few years earlier. To be fair he makes mostly good use of them, and some of the boy's more anguished speeches are interestingly written and evoke a palpable sense of "otherness". But it remains a quite derivative piece over all. Thankfully cast and crew elevate it.
Ironically, a year later and on the other side of the Atlantic, the "Charlie X" episode of Star Trek came to closely resemble Stranger In The Family - both had an unstable, sexually jealous telepathic teenager unable to suppress a psychic rage. It seems MANY owe John Wyndham A LOT one way or another.
Nevertheless, full marks to the cast and crew of this BBC production.