An actor capable of achieving whatever he aims to do within a proscenium, Rylance plays Valere, a buffoonish actor-playwright in 17th-century France who has been commanded by the Princess (Joanna Lumley) to join an acting troupe headed by court favorite Elomire (David Hyde Pierce).
As Valere retires after dinner to talk to Elomire and aide Bejart (Stephen Ouimette) in Elomire's library (designed by Mark Thompson as a high-ceilinged room dominated by tall bookshelves which contain several hundred books), Rylance -- who has been gotten up by Thompson in comically gaudy garb -- delivers a virtual half-hour monologue that's instantly an acting highlight of this (or any) year. It's a non-stop avalanche of bleated, hiccuped, cajoled, giggled, snorted, honeyed, and harangued words -- a flight of inspired fancy that isn't even curtailed during Valere's unembarrassed use of a just off-stage chamber pot.
Once the monologue concludes, though, Hirson begins to more strongly make his point about the rise of mediocrity and decline of excellence, which may even be more relevant today than 20 years ago. Elomire (an anagram for Moliere) convinces the Princess to have Valere present one of his plays -- this time using Elomire's players (Sally Wingert, Robert Lonsdale, Lisa Joyce, Michael Milligan, and Liza Sadovy) -- and to use this makeshift production as the deciding factor as to whether Valere should join the troupe.
Unfortunately, the primary drawback of La Bete is that Hirson can't refrain from being didactic. Elomire's final outcry about the damage the Valeres of the world do and the debasement they represent may well be true; but it's heavy-handed, especially coming after the enactment of Valere's unintentionally tedious play.
While the extraordinary Rylance is the primary reason not to miss La Bete, he's more-than-firmly supported by Hyde Pierce, who's more swaggeringly masculine than his Frasier followers have ever seen him; by Lumley, who couldn't be more regal and who still retains the blazing egotism she exhibited as Patsy in Absolutely Fabulous; and by Greta Lee, who is amusing as Dorine, a maid who's almost entirely lost the use of speech, a hang-up that is first milked for laughs but ultimately becomes a scary symbol for Hirson's point about the misuse of language.