If the plays of George Bernard Shaw are more admired than staged these days, this one may explain why. A National Theatre production, it weighs in at more than three and a half hours including interval, because it includes the third act - an extended dream sequence known as Don Juan in Hell, which is usually dropped (it didn't even make the premiere production).
What's more, the original includes a preface about a quarter as long as the play itself and an appendix adds the full text of the Revolutionist's Handbook and Pocket Companion, a book supposedly written by the main character, Jack Tanner: in both, Shaw rehearses many of the ideas that animate the play itself.
To modern ears, this can seem like unconscionable verbosity - I confess I found Act III wearying - and Tanner must surely be in the front rank of the theatre's most relentlessly garrulous characters. (Fiennes' fluent performance is, above all else, a titanic display of memorisation).
But Shaw, who rejected the frothy conventions of the late Victorian theatre and subtitled the play A Comedy and a Philosophy, was offering something more substantial than an evening's light entertainment.
For all that, there's a bracingly modern feel to the piece, a treatment of the Don Juan story that upends the gender roles and argues what anyone should know by now: that, in affairs of the heart, women pursue and men are prey.