LaBute minus shock appeal

Imagine, Neil LaBute suggests in his implausible immorality play about love and mendacity, that a young married man realises the terrorist attack on the World Trade Centre offers him a golden opportunity to abandon wife and children for the sake of his older mistress, Abby: what could be easier for John Hannah's immature Ben, who is adulterously down-town at the fatal hour, than to take advantage of fate and never go home, thereby leaving his family to assume he died in the bombing.

This scheme sounds more dramatic and immoral in theory than The Mercy Seat makes it in practice.

Three of LaBute's fascinating, earlier plays, The Distance from Here, The Shape of Things and Bash - already presented at the Almeida - offered believable insights into acts of cruelty or violence perpetrated without a twitch of conscience.

Yet In The Mercy Seat, to which Sinead Cusack brings abundant nervous tension, the claims that Ben makes to justify his cruel stratagem of disappearance and escape never convince. In fact disbelief puts in an early appearance, hangs flamboyantly around and refuses to leave.

The scene is Abby's Manhattan apartment, which designer Robert Jones makes the handsome model of luxury loft-living. On the day after the Twin Towers catastrophe, Ben broods on a sofa, ignoring the ringing of his mobile phone.

There is, crucially, no serious arguing over Ben's refusal to tell his wife the truth and Abby's conviction that he must. And in the final, revelatory scene the defecting father bizarrely claims it better for his daughters to think him dead than that there should be a long custody battle.

There is nothing in LaBute's characterisation to explain why a man who professes love for his children should be prepared to abandon them for ever. But then motive is the missing link in The Mercy Seat.

Instead the play deals with the unshocking and traditional question of adulterous, needy lovers, about to share their lives, uncertain about the quality of the passion that has united them.

Michael Attenborough's production vividly conveys the tempestuous volatility of the couple's relationship. Ben, employed by Abby and her intellectual inferior, emerges as an evasive, self-deceiver in Hannah's impassioned performance.

Miss Cusack's superb Abby registers signs of dismay as her lover's flaws are revealed. But this is LaBute without his serious shock appeal.

The Mercy Seat