It is so hard to write about this excellent comedy thriller without giving something away. Needless to say the final episode in which the loose ends have to be tied up - probably around one of the cast’s necks – is the toughest to discuss. One slip and the game may be given away.

In the old days a review could run after a screening because the main chance to see the programme had passed. But with catch-up you might see Stag at any point while it is on iPlayer. The only thing I can say without fear of giving a spoiler away is that you should definitely see it.

It is interesting that Reece Shearsmith featured in this mix of horror and comedy because I haven’t had a reviewing problem like this since that other recent great genre-bending twist-in-the-tale BBC series, Inside No 9. Like Inside No 9 the horror here often shares equal billing with the comedy. In the final episode more members of the stag party are bumped off in suitably grisly ways and for quite a while we are still left wondering whodunnit, Agatha Christie-style.

Not surprisingly social media has been fizzing with theories. But writer/director Jim Field Smith and co-writer George Kay have managed to pop in plenty of twists, turns and rug-pulls. As the surviving friends – Stephen Campbell Moore, JJ Feild, Jim Howick and Amit Shah (pictured) – attempt to get out of the woods you never quite know whether something is a red herring or a booby trap planted in the plot to trip the viewer up.

Along the way the dialogue remained as snappy as ever, with a daft quip about pylons, a neat joke about Saving Private Ryan and great sight gags involving an Irn Bru bottle and a water bottle among the Highland highlights. Gradually all becomes clear as the action builds to a very satisfying ending. There’s only really one disappointment. Given the high – and gruesome – corpse count it’s not going to be possible to reassemble the characters for a sequel. Maybe Field Smith could do Hen though...

Watch Stag on iPlayer here.