By Dominic Casciani BBC News Online

The play asks more questions than it gives answers

Franco Zeffirelli and Joan Plowright return to London's West End after a quarter of a century and 10 years respectively.

And what a way to do it with a great piece of absurd Italian theatre that leaves you not entirely sure of yourself, never mind what you have just witnessed.

Absolutely! (Perhaps) is a new translation by Martin Sherman of one of mischievous Italian playwright Luigi Pirandello's most bewildering works - Cosi e (Si vi pare!)

Previously known as Right You Are! (If You Think So), the Nobel laureate's sardonic tale retains the power to bamboozle and confound almost a century after it was written.

The play asks what happens when suspicious minds, with an obsession to know everything that is unknowable about others, try to discover the difference between fact and fiction.

Signor Ponza (Darrell D'Silva) arrives in a new town with his mother-in-law Signora Frola (Plowright) and a mysterious hidden wife, after apparently surviving an earthquake elsewhere.

His neighbours feverishly speculate why he hides his wife away.

And why on earth does Signora Frola cause great insult by declining to receive a coterie of nosey matriarchs, led by the glam-frump of Signora Amalia (Liza Tarbuck).

As the characters in the gossipy Sicilian town discover to their cost, you can never really know anything for certain: Is it your neighbour who is clinically insane or perhaps yourself? And what happens when the only certainty is found in contradictions?

Mischievous figure

As the rumours fly of devilish behaviour and a mysterious past, only the semi-narrator figure of Professor Lamberto Laudisi (Oliver Ford Davies) stands back from the parlour games.

Oliver Ford Davies: Part narrator, all mischief

That is, until he decides, just like Pirandello himself, to stir things up for his own amusement.

What is clear (or not clear as the case may be) is as Signora Frola and her son-in-law are asked to explain the truth, the truth becomes almost impossible to explain.

By the climax (which would be impossible to give away even if I tried) the boundaries between fantasy and reality, truth and lies and even the audience and the stage are completely gone.

Is Ponza as mad as a hatter - or are his inquisitors blind to an illusion within themselves?

Ford Davies' Laudisi comes closest to explaining when he chides his gossip-obsessed family for being trapped in a labyrinth of purgatory where they "watch fantasy and reality dance together and can't escape".

And if that does not help you, do not expect any answers in the staging. It confuses with mirrors, geometry and members of the audience invited to sit in the set.

Zeffirelli then shakes things up with a few surprise devices and even a dig at Latin sexual politics through the fine supporting cast, including Anna Carteret and Gawn Grainger playing the squabbling Sirellis.

So while certitude is something that Absolutely! (Perhaps) does not deal in, it is certainly an enjoyable night.

Go for the farce or go for the philosophy. Either way, it will still run rings around you and you will be glad that it did.

Undoubtedly it is Zeffirelli himself who is reminding us all that he remains the master illusionist.

He watched the opening night from a box, before revealing himself to take the applause.

Or was that really him? I don't think any of us were really sure by the end.