Griffin has been tooling around for nearly a year with his father’s ashes in the trunk, but his mother is still very much alive, and not shy about calling on his cell phone. She does so as he drives down to Cape Cod, where he and his wife, Joy, will celebrate the marriage of their daughter Laura’s best friend. For Griffin this is akin to driving into the past, since he took his childhood summer vacations there, his parents’ respite from the hated Midwest, and the Cape is where he and Joy honeymooned.      But by the end of this perfectly lovely weekend, the past has so thoroughly swamped the present that the future suddenly hangs in the balance. And when, a year later, a far more important wedding takes place, their beloved Laura’s, Griffin’s chauffeuring two urns of ashes as he contends once more with Joy and her large, unruly family, and both he and she have brought dates along. How in the world could this have happened?