DIANA RIGG is clearly having enormous fun playing the crime-solving psychologist in this new series, looking elegant and dropping superior aphorisms from perfectly made-up lips.
She also has a disconcerting habit of addressing them to the audience, mid-detection - a clumsy device, presumably to let us know we're not meant to take any of this too seriously. No danger of that.
Every detective needs a sidekick, but Mrs. Bradley's - an all-purpose chauffeur-cum-pickpocket called George - is almost as clever as she is.
Together they are, well, rather smug. So are Hercule Poirot and Sherlock Holmes, but at least their all-knowingness is tempered with comic eccentricities. It's no fun if the sleuths get to be glamorous and slick as well as brilliant.
The rest of the characters are as complicated as the suspects in Cluedo, leaving you free to admire the frocks and furnishings, which are suitably glorious, if at times a little odd (Mrs. Bradley wears a startling scarlet hat and leopard skin coat at one point).
But despite the conventional setting - a mistress in a girls' finishing school is killed, conveniently, as Mrs. B is giving a talk - the plot is rather quickly dispensed with in favour of quite a lot of innuendo.
George (Neil Dudgeon) strips off for a nude modelling session, to the lascivious delight of the schoolgirls and his employer, a copy of Radclyffe Hall's The Well Of Loneliness reveals a lesbian affair and Mrs. Bradley then goes on to speculate about bisexual menages a trois without turning a hair.
You would not be at all surprised to find the detective and her loyal sidekick going at it hammer and tongs to celebrate solving the crime (the scholarship girl did it, as always).
This was certainly more realistic than Agatha Christie, but I'm not sure if that's what anyone wants from a nostalgic murder mystery.
The genre is meant to be cosy and escapist, so after you get over the novelty value of all the sexy stuff, there's not a lot left here. Somewhere, Miss Marple is revolving genteelly in her grave.