After 30 years’ professional experience figuring out what’s going on in plays and why, The Height Of The Storm leaves me in the dark. I suspect that playwright Florian Zeller’s none the wiser. And this isn’t at all a criticism.

Zeller specialises in plays that demand an audience to do some active deciphering as they watch. He writes about our sense of identity, but instead of peering from the outside he works from the very core and shows all the contradictions and puzzles on the way out. His breakthrough play, The Father, portrayed a man with Alzheimer’s whose sense of self was becoming battered because he couldn't keep track of visits from his daughter.

The Height Of The Storm starts in a deliberately similar place: an elderly man (named André as in the earlier play), his focus failing, being visited by his daughter (again called Anne). Later a second daughter turns up, along with André’s wife and a woman whose name changes from mention to mention.

So what’s the mystery? Well, little passing remarks by various characters let things slip. There’s a suggestion that Anne wants André to retire to a residential home; perhaps plans have already been made to sell the rambling family house. This may be in André’s imagination, or someone else’s. Because what becomes comparatively (and I mean only comparatively) clear is that someone is dead.

It might be André himself, but it’s more probably his wife Madeleine. And yet not just he, but she and everybody else carry on conversations as if nothing were out of the ordinary. Well, except the things that are. But not that one. It’s... OK, I’ve run out of ways of saying it’s enigmatic.

What keeps us connected to this labyrinth are Zeller’s plain language, Jonathan Kent’s straightforward direction and above all the two brilliant central performances. Jonathan Pryce as André seldom alludes to, much less openly accepts, his condition; he takes refuge in grumbling and in lengthy quotation, probably from celebrated writer André’s own works. He is at his most relaxed in the company of Madeleine, whose ambiguous status and mercurial temperament Eileen Atkins portrays seemingly effortlessly; it’s not often one can say Pryce is outshone, but it happens, discreetly, here. Amanda Drew and Anna Madeley are far from villains, but their filial love in each case has its limits.

The brief coda is the key: André and Madeleine left alone, quietly hymning their closeness through their 50-year marriage. Alive or dead, the pair survive as a composite entity, defining each other as well as themselves. As I said, it’s a play that’s almost impossible to decipher, but it turns out not to be at all difficult to understand.

Written for The Lady.