Despite 2 strong performances, a clunky adaptation of a McEwan novel

The BBC/PBS adaptation (2018) of Ian McEwan's novel The Child in Time is notable for the fine performance by Benedict Cumberbatch of Stephen, a successful children's-book author (I would say he's writing for young adults, but it's never made clear) whose 4-year-old daughter disappears while he's out w/ her shopping for groceries. The movie - which I believe is extremely faithful to McEwan's novel, though I have not read the book - deals with the aftermath of this abduction, in particular to its effect on Stephen's marriage to Julie (Kelly McDonald, in a strong performance as well). Two strong performances, then - but is that enough to make this movie worth your time? Not in my view. For whatever reason, this novel dos not translate into film, or at least not into this one. For one thing, though the film is seemingly realistic there is at least one segment that seems mystical and supernatural - completely out of sync w/ the rest of the movie and opening up - but not resolving - the possibility that the many "sightings" of the vanished daughter are mystical events as well rather than hallucinations, projections, and wishful imagining. Then there's the completely strange behavior of Stephen's best friend, supposedly a famous editor and high-ranking government employee, who is seriously mentally ill though for no apparent reason nobody seems willing or able to get him any help. Then there's the disappearance itself. I accept that this movie, though it looks like one at first, is by no means a police procedural; it's not about finding the daughter but about what happens to her grieving parents. Still (spoiler here), some explanation would be helpful; we in fact never learn how she disappeared, how she could have been abducted and vanish w/out a trace. Usually, BBC productions are known for their great production values, but a lot of things fall short in this one. For ex., the producers seemed unable to decide when these events took place; McEwan'sn ovel was published in 1987, and sometimes the movie looks to be of that era: walkie-talkie toys, no mention of email or websites or using the Internet to get info on the disappearance, travelers sending post cards rather than email, mailing a CD rather than sending a video, and so on. And then, when a plot point is needed, there's BC talking on his "mobile." There's an attempt at building a dramatic conclusion, visible from miles away, but at the end I just shrugged: Is that all there is?