As far as dying onstage goes, Bob Malos’ performance at Park Square in the premiere of “The Red Box” is at once essential to the plot and unwittingly droll. Malos plays avuncular boutique owner Boyden McNair, a suspect in the death of a model poisoned by candy at his shop.

Early in the show, McNair rushes into the office of detective Nero Wolfe (E.J. Subkoviak), a place where he had reluctantly been before. Now he appears ready to spill his guts. McNair grows short of breath. He collapses onto the floor and starts to retch, as if being strangled by invisible hands. Wolfe tries to help, but to no avail. McNair turns over onto his face, writhes and goes still.

It’s not giving much away to say we quickly learn that McNair was not fighting some unseen ghost; he had been poisoned. Before his death, he named Wolfe his executor, and also bequeathed a red box and its mysterious contents to the detective. The bequest is a holy grail and motivating idea. Wolfe competes with the police to find it.

New York-based playwright Joseph Goodrich adapted “The Red Box” from the fourth novel in Rex Stout’s Nero Wolfe detective series. He has condensed the action to one locale — Wolfe’s office (designed by Rick Polenek). He also has cut characters and made some plot changes to fit this work into a drawing-room mystery for the stage.

The production, which premiered Friday in St. Paul under Peter Moore’s able direction, is a fairly entertaining one. Moore keeps the action tight and light in a show that’s mostly a head game, anyway. And Moore’s actors all have good poker faces for characters with reasons to be peeved, if not to kill.

There is Helen Frost (Rebecca Wilson), the young heiress poised to inherit a fortune on her 21st birthday, who seems to lie about what she knows about the poisoned candy. The show also includes Lew Frost (Nicholas Leeman), Helen’s cousin who also has a romantic interest in her; Calida Frost (Susanne Egli), Helen’s mother who disapproves of her daughter’s closeness to McNair; and Dudley Frost (Jim Cada), Helen’s blowy stepfather.

All are potential murderers whose motives we quickly deduce.

The two-act production, narrated earnestly by Wolfe’s assistant, Archie Goodwin (Sam Pearson), keeps the suspense all the way through.

True, Moore’s staging is more suggestive than active. The fact that it has only one set means that it has to find other ways to keep us in suspense, and it does.

The cast is solid, anchored by Subkoviak as the smart, roly-poly problem-solver who would rather be tending to his orchids. If there are no standout performances in “Red Box,” there also are no stinkers. The show is a pleasant, diverting summer entertainment.