Sunday Father, Hampstead Theatre, London

At the start of Sunday Father, a new play by the Canadian dramatist Adam Pettle, a Jewish sports writer, Jed, discovers the infidelity of his wife Amy, a Gentile shrink. He moves out and tries to settle into a painful routine of seeing his four-year-old-son Daniel twice a week.

The main focus, though, is on Jed's close but troubled relationship with his older brother, Alan, a financial lawyer. They themselves are the damaged result of a childhood paternal walkout. We learn that the youngJed once promised his sibling that he would never get divorced. So is his current predicament evidence that we forget all the promises we make, as Alan says? Or is it the sign of a dodgy play that relies on contrived situations?

Rupert Goold's decent production is punctuated by excerpts from tapes the brothers recorded as children. These poignant, slightly spooky reminders of the past don't make it easier to credit that Jed (sympathetically played by Dan Fredenburgh) would expose his son to the same problems.

The wife (Raquel Cassidy) feels more like a dramaturgical convenience than a person. Given her work, it's odd that she shows so little psychological insight. She does not want Jed to leave, but when he does, she becomes harder - providing the opportunity for Alan to beg her not to put Daniel through what he and Jed experienced.

The staging cannot mask the clunkiness of the bits where, in the guise of reading myths and Bible stories to the unseen four-year-old, the characters descant on their own predicaments. It's tantamount to child abuse. For example, Alan treats the boy to a personalised bedtime rendition of the Cain and Abel narrative. Despite having to rise above some risible plot devices, Corey Johnson rouses pity for the disillusioned Alan, festering in the family law firm in a futile attempt to win his father's affection.

In a final hopeful scene, Jed and Amy watch their son playing in the park. Alan had joked that, for baseball purposes, Jed should force Daniel to be a left-hander. It seems the boy has become one naturally. Never prepared to allow suggestion to do the work of thudding explicitness, Sunday Father has Amy draw an analogy with her relationship to Jed. She's felt warmer towards him lately, because he's just "let her be". It's a moral not digested by this play, which makes strenuous efforts to manipulate our responses at every turn.

To 9 Aug (020-7722 9301)