Arsenic and Old Lace, Bog Theatre, at Metropolis Performing Arts Centre. Careful plotting and broad humor rooted in the macabre keep Joseph Kesselring’s 1941 farce popular despite dated jokes about Hitler, Boris Karloff, and Judith Anderson. In this smart, eccentric comedy, the nephew of two sweet old ladies is horrified to discover that his darling aunts are killing gentlemen callers as an act of “charity.” Mortimer’s efforts to protect them are hindered by their cheery pride in their crimes and the unexpected arrival of his violent, insane brother Jonathan.

In this Bog Theatre staging, one of Metropolis’s first coproducing efforts, Nancy Greco and Barbara Stasiw are funny as the feisty spinsters but play them too young: sporadic attempts to convince us their characters are sweetly muddled elderly ladies come across as affected. They do grow on us but never enough to carry a play centered around the Brewster sisters’ addled belief that they’re doing good.

Also, director Daniel Scott needs to find a more consistent tone. Fred Haas as the frenzied Mortimer, Dan Loftus as Jonathan’s tippling sidekick, and Paul Margolis as the Brewster who believes he’s Teddy Roosevelt throw themselves into the farce, but regrettably the rest settle for calmer comedy. The approaches meld as the script’s silliness mounts, but swifter pacing and greater vigor would earn this merely adequate production a more enthusiastic response.