The opening scene focuses upon a staircase, down which silently treads a man, gun in hand. For all we can tell, this is a seedy lodging house whose worn carpet is about to be decorated by blood.
In fact, a door opens upon a Sunday-afternoon suburban sitting room where a Red Indian - some ten years old - gives a whoop of surprise at being caught out by his father (Patrick Holt) who, no cowboy, is in fact a features editor whose wife (Honor Blackman) is so engaged upon some sewing that she asks him to make the tea.
A task which coincides with the telephone ringing in the hallway (its then customary location): the fashion writer with whom he has had an affair the past three years, of which he now wishes the peaceful end he appears unlikely to find. In hopes of doing so, he arranges to meet her the following evening under cover of a visit to a former Army friend with whom he has racked up gambling debts.
Nothing goes to plan, not least because a key role is played by a nosey parker who delights in her party line: the telephone deserves a credit of its own, alongside all those small players, such as a bluff porter at a block of flats, who help to propel the twists of the plot. Their names mean even less now, and at the time were perhaps otherwise engaged upon repertory theatre, but without them such films would not exist.
Needless to say, events take a turn which brings in the Yard, personified by an Inspector, Valentine Dyall, an actor who could switch between good and evil with ease. How pleasing it is for those of with a taste for such films to find him in this one - along with night scenes, telephone boxes, black cars with scant regard for KEEP LEFT signs, trains whose pelting smoke is oblivious to climate change, not to mention well-stocked shelves where spirits overshadow sherry.
All this occupies but 65 minutes, no detail of which can be overlooked, and one can imagine that, within a few years, writer and director would have been obliged to stretch it out, to less effect.
This is adroit film-making which recognises that nobody - on the screen or behind it - should predominate.