“SOMETHING terrible has happened.” The most frightening event, the creepiest source of terror, is the one that cannot be put exactly into words — a truth brilliantly manifested in the works of that great intertestamental scholar M. R. James, and now given a new outing in BBC2’s lavish retelling of Picnic at Hanging Rock (Wednesdays).

The first episode ended with the tragic return from the day out, the three star pupils of the Academy missing, the only witness to what happened (or did anything actually happen?) so scared as to be capable only of uttering the words with which this review begins.

This is a no-holds-barred version of the story, visually spectacular in saturated hyper-colour. The Boer Ward period detail is lovingly recreated in settings, costumes, and attitudes. These young ladies are on the very cusp of life, maidens becoming adults, in thrall to uncomprehended forces and impulses.

The requirement that they act like genteel English ladies is undermined by their school’s hothouse atmosphere; their virginal white dresses, which become a snare and an encumbrance; and a native landscape that holds far older, darker forces — the Rock itself is able to make time stand still, and to engender visions.

And what is the Principal, Miss Appleyard’s, dark secret, flagged up and hinted at as the mists swirl, the kookaburras shriek? Perhaps you have picked up my difficulty here: there are simply too many themes, each powerful, but jangling and clashing with each other, undermining the inexorable and steady build-up so essential to the genre.

The absolute opposite setting played a vital part in The Rise and Fall of Nokia (BBC4, Tuesday of last week). Finland’s endless birch forests and lakes engendered the coolest possible background to this morality tale of spectacular growth and subsequent collapse, told by former team members; for this company really was a team, working together and sharing ideas, bottom up rather than directed top down, keen when presented with a difficult problem to go to the sauna with its wonderful view and wait for communal inspiration.

But unimaginable success bred ruthless competition, enormous bonuses, and outsiders hungry only for success and wealth rather than quality — and then the iPhone dealt the death blow.

Horizon: How to Build a Time Machine (BBC2, Tuesday of last week) may hold the clue to how we might foresee, and avert, future disaster; but not any time soon. This covered all the usual phenomena: the potential warping of the space/time continuum; wormholes and dark matter; the mystery of why the expansion of the universe is hastening rather than slowing down; and, above all, the basic question: What is time, anyway?

The standard scientific response is that time is an illusion, a human construct. Most refreshingly, the programme found a scientist who disagrees: who thinks that time is, indeed, a successive flow of real moments, and that his colleagues are tricked by mathematics into believing something that is clearly false.