Each main protagonist in Florian Zeller’s trilogy of family angst suffers from a debilitating state of mind. In The Mother it was loneliness, in The Father it was Alzheimer’s and in this final work in the series it is a teenager’s fathom-deep depression.

Though Zeller wrote the works in the above order, the first to make it to these shores (and to be translated, as most of his plays have been by Les Liasons Dangereuses adaptor Christopher Hampton) was The Father, a brilliantly constructed insight into what it is like to live with a memory-dissolving disease.

Looking back you can see that London producers wisely chose which play to introduce this talent to British audiences. But although the reputation built by Zeller’s UK premiere in 2014 has proved to be deserved - both After the Storm and The Lie reach inside the heads of his protagonists by ingeniously subverting a play’s structure — The Son is the least clever of them all.

The erratic behaviour of teen Nicolas (Laurie Kynaston) forces his estranged parents Pierre (John Light) and Anne (Amanda Abbington) back into each other’s lives. Anne has custody but no authority over her son. Nicolas has been playing truant for three months, and the stares he gives her are increasingly intimidating. Perhaps he should live with Pierre, a potentially awkward suggestion given that Pierre now lives with Sofia (Amaka Okafor) with whom he has a baby son.

Kynaston terrifically transmits the desolate state of being outwardly normal and inwardly life-phobic. But aside from the cool chic conjured by Michael Longhurst’s production — as so often with Zeller, the action is set in minimalist Parisian apartments — the evening boasts few of the virtues of Zeller’s other plays. Most conspicuously absent here is the writing flare with which Zeller keeps this audiences off balance. And unless you have never thought about how divorce affects children, you will not leave theatre with a better understanding of that kind of collateral damage.

So who then does this play exist to enlighten? Could the target audience be from a society where affairs are so conventional that the very idea there might be a moral case against such behaviour is hardly ever entertained? It fells like it.

There are other niggles. Light is pretty good as Nicolas’s lawyer father, the urbane, metrosexuality always in danger of failing to control his suppressed alpha-male aggression. And Abbington does well with an under-written role that has little more to it than a mother’s love and fear for her son. But the decision made by these rational parents, which lead to the play’s heavily signalled climax, is a bit too stupid to credit them with the sympathy that Zeller invites.

I’m still a fan. But had this been the play that introduced this clearly very clever novelist and dramatist to the English stage, he might have been forgotten by now.