Freddie Thornhill (Sir Ian McKellen) and Stuart Bixby (Sir Derek Jacobi) are an old gay couple who have been together for nearly fifty years. Their lives now revolve around entertaining their frequent guests and hurling insults at each other at every opportunity.
As a jazz musician might do something lovely even with a banal melody, McKellen and Jacobi - baritone to tenor - make beautiful, dissonant music together.
Leave your politically correct concerns on the doorstep, sit back, and let the venom wash over you like a sleet storm. McKellen and Jacobi, who are, of course, giants of their profession, are clearly having a lark with Vicious.
McKellen turns out to be the show's not-so-secret weapon. A great actor playing a mediocre one, he's somehow entirely convincing in the part and particularly adept at delivering Janetti's acid-tongued putdowns and sarcastic asides.
Vicious is an apotheosis of the form: Its theatricality is expert, its rote insult comedy is delicious but not unyielding, and its unhip datedness is mined for exactly that quality.
Line-for-line, Vicious would seem depressingly outdated and especially boring if delivered with American accents; but it somehow takes on a whiff of Oscar Wilde-like charm simply because it's British.