Trouble comes when Carl (Marc Shule), Sam's son and Zach's father, arrives intending to commit Sam to a nursing home. Costumed like a mobster (black slacks and shirt, shiny blazer), Carl inspects the premises like a crook casing the joint, opining malevolently and challenging Zach to persuade Sam to agree to move by "closing the sale." Later, that sinister side just slips away.

The play eventually focuses on the relationships between fathers and sons: Why, Carl asks, doesn't Sam acknowledge his late wife, Carl's mother? Why does Zach delay his independence, preferring a comic book shop gig and caring for his grandfather to an education and career? Why is Carl so opposed to Sam marching in a Memorial Day parade?

The wisest lines—in both the comedic and weighty senses—go to family friend Pete, played engagingly by Jerry Puma, who admits, "Sometimes just because something's the right thing to do doesn't mean it's not a shitty thing to do." Pete spends his days coloring with Sam—both wear silly hats to "keep our brains from freezing up"—which ultimately becomes a metaphor for processing the past and breaking the ice between estranged generations.

Director Robin Eisenberg's production doesn't help, with awkward staging in the small Mum Puppettheatre space, an over-reliance on yelling and a poorly executed sound design that creates awkward silences as actors bumble into place during blackouts. Daniel Krause's perfunctory scenic design isn't helped by Sam's blandly childish drawings taped all over the walls, which don't seem created to express the inner turmoil he's meant to explore.

The Biggest Box of Crayons is a nice play that doesn't plumb its implied depths. We're left wondering about every character's smoldering resentments and compromised decisions without ever breaking through to genuine insight and understanding.

The Biggest Box Of Crayons

Philadelphia Theatre Workshop, through May 7, Mum Puppettheatre, 115 Arch St., 215-635-2137 or www.philadelphiatheatreworkshop.org