“PRAYING MANTIS,” Thursday at 8 p.m. (50),...

“PRAYING MANTIS,” Thursday at 8 p.m. (50), and at 9 p.m. (28) (15)--Public TV’s “Mystery!” series, offering productions that range from the brooding and cerebral “Reilly: Ace of Spies” to the lighter-hearted “Rumpole of Bailey,” continues to be swell viewing.

And the three-part “Praying Mantis” (starting Thursday night) is no exception. This one features some of the more Murderous, sinister and amoral characters seen on TV in some time in a suspenseful, mysterious and almost comically ironic puzzler that is let down only by a weak conclusion.

Here is a story that exhausted its twists before the ending. Yet the three-episode trip is so much fun and so stylishly executed under Jack Gold’s direction that the conclusion and occasional unexplained story holes turn out to be only minor and tolerable disappointments.

The mantis in the title refers to a female insect that devours its mate. And indeed the women in thes sophisticated story, adapted by Philip Mackie from Hubert Monteilhet’s novel, are predators deluxe.

Carmen Du Sautoy plays the treacherous wife of a well-meaning university professor, portrayed by Pinkas Braun, and Cherie Lunghi plays his plotting secretary/lover. The women are almost amusingly wicked, but most certainly lethal. Jonathan Pryce plays the professor’s assistant who . . .well, you’ll find out soon enough. Suffice to say that the professor’s million-dollar insurance policy puts him in jeopardy.

The performances, especially by Du Sautoy and Lunghi, are impeccable and “Praying Mantis” reflects the kind of layered, subtly crafted characters that we take for granted in the best of English productions. Little here is what it seems.

Except for fun.