On the walls of the old woman’s apartment are spaces where paintings used to hang; on its shelves are books, LPs, jars of a murky unidentifiable liquid, but no family photos.

Before the The Velocity of Autumn even begins, we have questions. Playwright Eric Coble will answer them all in his two-actor drama with comedic touches, dexterously directed by David Wolber at Matrix Theatre.

The mysterious liquid turns out to be developing fluid, that archaic but still volatile photographic chemical. It’s also a plot developer: Alexandra (Jane MacFarlane), full of fury, is threatening to use it to blow herself up and with it the brownstone she owns in Brooklyn’s fashionable Park Slope. Her children believe, with some justification, that she can no longer take care of herself. They want her to sell the valuable building and go someplace where she’ll be cared for. She wants to die at home, and if it comes quickly by her own hand, so be it.

Enter an unconventional man in an unconventional manner: her long-lost son Christopher (Chris Korte) climbs through an open window when Alexandra ignores the doorbell. Besides, she has barricaded the door.

What ensues, besides the will-she-or-won’t-she suspense, is a wide-ranging conversation that covers the insults, both physical and mental, that come with aging; holding on, letting go, loss, estrangement, acceptance, art, travel, about empty spaces where something used to be, and reaching a point in life where “the only thing you have to offer is to stay out of the way.”

Mother and son are both artists and the discussion can get esoteric, but these moments are redeemed by some beautifully written passages. Korte makes the most of a lovely description of a Navajo sand painting, while MacFarlane displays similar eloquence talking about how walking up (or down) the curved ramps of the Guggenheim Museum can change the way one looks at a single painting or a group of paintings.

The script abounds with such metaphors for life and the ways it may be approached. To the credit of Wolber, MacFarlane and Korte, the play rarely feels talky. Quiet moments are mixed with outbursts; the actors range far across a wide, shallow stage, and there is Alexandra’s ever-present Zippo lighter and those jars of exploding liquid. Things heat up and could blow up at any time.

Coble tosses in just enough cultural references to establish the kind of upbringing Alexandra and her late husband provided their children (two other siblings phone but are never seen or heard): Rumpelmayer’s, a long-gone dessert place for good (and well-off) little boys and girls; the weekly Metropolitan Opera radio broadcast with its opera quiz hosted by Edward Downes.

A tad more New York authenticity is provided with subtlety by sound designer Neil Koivu: the occasional pigeon cooing outside the open window or a passing police or fire siren.

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