Amyas Crale was having an affair. So his wife, Caroline, killed him. It was, apparently, that simple. Caroline went to jail, and that was that. But several years later, the convicted murderer died, and left a note to her daughter, Carla, explaining her innocence. Now Carla, at 21, has the letter and wants to find out what really happened.

That sets the stage for Agatha Christie’s drawing room murder mystery “Go Back for Murder,” playing thorugh Aug. 29 at the Acadia Repertory Theatre in Somesville.

Intending to clear her mother’s name and calm the nerves of her fiance (who’s not thrilled about marrying the daughter of a killer), Carla decides to restage the murder. She invites her father’s former mistress, her mother’s half sister, the governess, and two close family friends, all of whom were present at the family home in England at the time of the murder. The action follows a series of flashbacks to reconstruct the whodunit and whytheydunit plot.

Christie’s work has always provided the most popular shows of the season at Acadia Rep, and “Go Back for Murder” will probably sate many sleuth-loving theatergoers. But it is not director Ken Stack’s strongest production of the season, nor is it as lavishly or expertly presented as past offerings in the genre.

Simply put, the show is sparse. The actors, including lead performer Alexandra Loria as Carla, lack the overall sharpness, underlying slyness and enduring robustness of Christie’s characterizations. In Loria’s case, it’s quite obvious that she has the hardiness of a heroine brewing within her husky voice and animated features, but her acting falls too often into empty stage tricks: poses and voice modulations that are mostly uninteresting.

The cast in general, however, is quite amateurish, and one gets the feeling that Loria could do better if she were surrounded by greatness.

Thankfully, the energy and oddity of Ted Cancila as Jeff, Carla’s fiance, give a charge to the first act. Strange though his enlivened and brief cameo appearance is, it is filled with humor and bigness, which is missing from too many of the other performances.

Similarly, Lou Solomon has a handle on the characterization of poison-providing Meredith Blake. Unlike many of his cast members, Solomon is at ease with his actions and the solidity of his persona, so his work onstage seems quite natural. The same could be said of Eugene J. Tierney as Amyas, who really picks up the pace of the second half. These guys know what they are doing, and it shows.

The sparsity carries over into the design of the show, too. When a set is designed with a very minimum of pieces — a desk to represent a lawyer’s office, a stone wall and wicker furniture to represent a country home — then the actors really must fill in the space with imagination and excitement.

But this production moves along more like a board game, with all the symbols of a murder mystery, and the flat players to match.

“Go Back for Murder” will be performed 8:15 p.m. Tuesday-Sunday through Aug. 28, and 2 p.m. Aug. 29 at Acadia Repertory Theatre in Somesville. For tickets, call 244-7260.