Missing: Beyond the Vanishing Triangle review – doubly frustrating account of the Annie McCarrick case

It is the very awfulness of the stories they tell that makes these crime documentaries questionable. We have absolutely nothing to offer these grieving families after all these years except our utmost respect. So, little details take on a heavy significance. First of all, the shape marked out by the programme makers on a map with red thread wasn’t actually a triangle at all; it was parallelogram — sort of.

No amount of pulsing strings on the soundtrack could make what we saw a triangle. As a viewer, you kind of lost heart at this point, in the very opening minutes. And what is a vanishing triangle anyway? Was it just a label thought up by some bright spark in a newspaper who was trying to evoke the Bermuda Triangle? Anyway, last night the triangle itself was seen to have indeed vanished.

Then there was the moment, towards the end of the programme, when Nancy McCarrick, whose husband and only child are now both dead, decided this year, on the 30th anniversary of Annie’s disappearance, to write to Garda Commissioner Drew Harris, asking that the case be designated a murder investigation.

The voiceover told us that Mrs McCarrick was “requesting an upgrade”. This was an unfortunate turn of phrase to use about a grieving mother, as opposed to a cheeky passenger looking for a promotion to the first-class section of a plane. These things matter a great deal. When you have nothing, you can still keep your eyes and ears open.

And it was hard to tell what Missing: Beyond the Vanishing Triangle actually had. The retired gardaí who had been involved in the McCarrick investigation were all convinced that they had done a good job. The grieving family and friends in America couldn’t understand why their questions and their faxes had gone astray and nobody seemed to be talking to anyone else.

The appalling killings of Patricia McGauley and Mary Cummins were covered at speed. This was presumably because they were eventually solved, due to a combination of good detective work and a lucky break: a woman came in to Ronanstown garda station in Dublin to make a complaint about a serious assault by the man who, it transpired, had killed McGauley, who was his partner, and Cummins.

There are questions of the utmost importance to be asked here, about violence against women — both domestic violence and random violence — and how that violence is treated by the gardai. Annie McCarrick was being harassed by someone she knew. Patricia McGauley was the partner of a violent man who went on to kill another woman.

Presumably we can look forward to some serious analysis in the second and final episode next Monday.