In Act 1 it's 1959, and we meet the white family who sold the house to the Youngers on the weekend before their Monday move.
In Act 2 it's 2009, and we meet the gentrifying white couple who have bought the house. Now it's a black couple who try to discourage them, speaking for the community, wanting to preserve the character of their black neighborhood.
The more things change, the more they stay the same.
What has happened to Clybourne Park in 50 years is Norris' template for what happened to American society: Shifts in demographics do not solve race problems, especially among people who will not admit their racist attitudes - despite a wild scene in which they trade offensive racist jokes.
We watch the irritating, chirpy, saccharine 1959 mother (Julia Gibson) patronize her maid (Erika Rose): Both women keep a very tight rein on themselves, with their husbands (David Ingram and Josh Tower), and with each other. Karl Linder (Ian Merrill Peakes) - the only character from Hansberry's play to appear in Norris' - is, unsurprisingly, an obnoxious bully, married to a pregnant deaf woman (Maggie Lakis). This Father Knows Best world is rounded out by an ineffectual minister (Steve Pacek).
All these actors will reappear in 2009 as radically different characters, making Act 2 a fine display of virtuosity, demonstrating theatrically that everything changes and nothing changes. There's a trunk buried in Act 1 under a tree in the backyard, and dug up in Act 2. Much is buried in Norris' America - guilt and grief and hypocrisy and repression.
Clybourne Park is a play that both annoys and amuses; it creeps up on you and makes you squirm. It seems to be obvious and turns out to be subtle. It seems to be an easy setup and turns out to be complicated one. This is a bitter satire that makes us laugh while it indicts us.
Through March 25 at the Arden Theatre, 40 N. Second St. Tickets: $29-$45. Information: 215-922-1122 or www.ardentheatre.org.