BY CRAIG CHALLENDER

Special to The Farmville Herald

“There are six of you standing here before me. One of you is the killer. And one of you is the victim.” This pronouncement by Detective Sergeant Trotter, midway through Act Two of Agatha Christie’s “The Mousetrap,” fixes the inhabitants of Monkswell Manor as precisely as butterflies pinned to the board of a science fair project. By this point in the play we the audience are transfixed as well, though for different reasons; Miss Christie has seen to that.

“The Mousetrap,” the final offering of The Waterworks Players’ current season, began as “Three Blind Mice,” a 30-minute radio play honoring Queen Mary in 1947. It evolved into a short story, and finally a full-length play that opened in London’s West End in late November 1952. It’s still going — the longest run of any play in history, now nearing 30,000 performances. This Waterworks production would meet with the author’s approval.

Agatha Christie perfected the “whodunnit” formula in her novels and plays, and “The Mousetrap” is Exhibit A. The characters are types, two dimensional at best; it’s the plot that drives things, and that’s what we expect from mysteries, of course. What makes this play unique is the twist at its end, which departs from the whodunnit pattern: detective-solves-crime, detective-unravels-plot secrets.

“The Mousetrap” begins traditionally enough. The setting: Monkwell Manor, a grand old place converted to a guest house by its new owners — and newlyweds, Mollie and Giles Ralston. Outside, a winter storm is gathering; inside, a radio crackles with details about the murder of a woman named Susan Lyon. One by one the guests for the night appear, quickly sketched in by their singularities: Christopher Wren, a strange, hyperactive young man; Mrs. Boyle, a grumpy grande dame; Major Metcalf, a retired army officer; Miss Casewell, a mannish, brusque bulldozer of a woman; and Mr. Paravicini, an avuncular Italian (maybe) who declares himself “a man of mystery” that “completes the picture” of this odd assortment. Not so subtly linking the guests are their clothes, variations of what the suspected murderer was wearing: “a dark overcoat, a scarf, and a soft … felt … hat.”

Spoiler alerts are strictly forbidden in whodunnits. Suffice it to say that “The Mousetrap’s” two acts, each just over an hourlong, move quickly. Our attention is held not only by the plot’s twists and turns but also by our changing perceptions of each character, brought about by Sergeant Trotter’s incessant questioning. As Mollie cries near play’s end: “Perhaps I can’t trust anybody … perhaps everyone is a stranger.”

Kudos to the cast, a nice blend of Waterworks veterans and newbies. John Burton and Tehya Cifers are simpatico as Giles and Mollie. Their onstage chemistry shows even before the play starts, thanks to an innovative directorial decision. (Try to find your seats at least 10 minutes before showtime.) Randall Linkins, in his Waterworks debut, is an almost literally “flighty” Christopher Wren. Jeffree Hudson, with more than 35 Waterworks credits behind her, has a grand time as the dyspeptic Mrs. Boyle. (“A lot of people have got dry rot and don’t know it” is a characteristic verbal jab.). Mike Montgomery is a solidly British Major Metcalf. Christy Moore as Miss Casewell makes the most of her first serious Waterworks role. (When Giles describes her as “a terrible female — if she is a female,” we tend to agree with him.) Billy Tucker, memorable as the Russian Molokov in “Chess,” adds an ersatz Italian to his repertoire as the funny-yet-sinister Paravicini. Finally, David Standley is wonderful in his stage debut as Dectective Trotter: a crisply profession interrogator who later … this is why we must stay tuned.

Kudos as well to the production team. Agatha Christie aficionado Scott Chapman, whose Waterworks debut last summer was Christie’s “And Then There Were None,” wears two hats this time: director and lighting designer. “Mousetrap” moves well and the lighting enhances Moffatt Evans’s set, which as usual is a marvel — spacious and claustrophobic at the same time. Erika Evans (costume design) and Hannah Boswell (production seamstress) have fashioned clothes that make the man (or woman) and help create the illusion of a time long past. Finally, Chris Brochon pulls double duty as sound designer and as the radio voice that opens the play.

“The Mousetrap’s” final performances are this weekend, Friday and Saturday, at 8 p.m. For ticket information go to the Waterworks website, waterworksplayers.org, or call (434) 392-3452.