“It’s all melodramatic rubbish!” declares Mrs. Boyle (Barbara Plymale) early on in Chamberlayne Actors Theatre’s production of “The Mousetrap.” And certainly, Agatha Christie’s popular whodunit is layered thick with melodrama, from the twitchy suspects to the stern police sergeant, to the mustache-twirling man of mystery. But it doesn’t have to be rubbish. In the right hands, this broad and veddy British play can be full of old-fashioned fun. Apparently, the right hands were not available for this production, however. The actors assembled by director Granville Scott vary widely in talent, and he never quite gets them working smoothly together. Though there are some satisfactory moments here, the lasting impression is one of a trap set but never sprung. The plot of “The Mousetrap” is a familiar one even if you’ve never seen the play. A hopeful young couple, Giles and Mollie Ralston (John Ramsburg and Lisanne Klim), open a guest house in a town outside of London on the day of a grisly murder in the city. A horrible snowstorm blows in, conveniently isolating all the guests from the outside world. As if that’s not bad enough, police investigator Sergeant Trotter (Bob Murphy) shows up on skis to announce that one of them is suspected of being the murderer. After one of the guests turns up dead, accusations fly and secrets are uncovered until the dirty-deed doer is revealed in a final surprising twist. Christie’s crafty plot has grown tired in the 50 years since its debut, but it is still stuffed full of enough intrigue, red herrings and smart self-parody to remain entertaining. One particularly impressive scene is a low-key tˆte-…-tˆte between the two female suspects, Mrs. Ralston and the sly Miss Casewell (Abigail Davis), where Christie manages to throw suspicion on both of them. The tension of this scene accentuates by contrast the weakness of most others in this production. Part of the problem is that each actor takes a completely different attitude toward his or her character. Davis comes off most favorably with her restrained and confident portrayal of Miss Casewell. Paul Newell, on the other hand, is too giddy by half as the off-kilter Christopher Wren. While Murphy displays a charming tenacity as the sergeant, Bruce Showalter plays the lascivious Mr. Paravicini so broadly he is barely one-dimensional. And as Mrs. Ralston, Klim is simply too scattered, ricocheting from hand-wringing worry when talking with the sergeant to demure receptivity in response to Mr. Paravicini’s flirtations. Judging by his direction of his actors, it’s hard to tell whether Scott is taking this play too seriously or not seriously enough. In the end, the confusion is frustrating. CAT’s resident set designer Lin Heath has done a typically fine job in realizing the well-appointed look of a 1950’s manor house. Shannon Baily’s lighting design was a bit glaring and could have benefited from a greater variety of tones. The cast, on the other hand, would have fared better with a greater consistency in tone. You may want to wait until some theater in town builds a better “Mousetrap,” instead of getting ensnared in this one.