Did Aristotle Onassis really conspire in the assassination of Bobby Kennedy in 1968? And did he do so out of cultural envy, sexual jealousy, business tactics, in deference to the PLO (with whom he safeguarded his commercial airline), or mere spite?
Martin Sherman's fascinating new play, battening on to all the outlandish suggestions in Peter Evans's racy Onassis biography, subscribes to the legend and compiles a modern Greek tragedy around the utterly mesmerising performance of Robert Lindsay as the shameless monster.
An animated dynastic wall-chart at the start of the play sets Aristotle Socrates Onassis, shipping magnate son of a Smyrna tobacco merchant, at delicious, ratty odds with the world he infiltrated and screwed over: the Kennedy clan, the Churchills, his rival Stavros Niarchos, Gloria Swanson, Marlene Dietrich and Maria Callas.
Opera reminded Onassis of Italian waiters shouting risotto recipes at each other, and it's one weakness of Sherman's play that Callas, played by a somewhat emaciated Anna Francolini, never sings a full-blooded rebuff, but dwindles into a shrill Cassandra dressed as Madam Butterfly, listening to her own recording of "Casta Diva".
Lydia Leonard's cleverly compiled Jackie Kennedy, on the other hand, outlines a sexually voracious social climber intrigued by Ari's account of a homosexual encounter allowing him to know what a woman feels in bed: he boasts that whereas most men pay women the compliment of dropping in for a visit, he inhabits the whole house.
Lindsay is trimmer and lither than Onassis, and has an over-worked habit of eliding into an Anthony Quinn-style sideways shuffle among his friends in the taverna, but he exudes unadulterated malice and horrible egoism.
Apart from the physical and vocal authority of an actor whose career is bookended by brilliant performances as the award-winning Cockney hoofer in Me and My Girl and the best Archie Rice since Laurence Olivier's in The Entertainer, Lindsay nails the self-serving ruthlessness of Onassis as slightly out of character; he's happiest on home territory, moving to music, flapping a napkin.
His tragedy is that he knows he's a human demi-god susceptible to divine retribution, but cannot deal with it when it happens. His life spins out of control after the death of his son (Tom Austen), which is presented with the mythical inevitability of Hippolytus in his chariot, and he retreats to oblivion after shipping tanker-loads of heroin around the world.
Director Nancy Meckler sets this riveting piratical performance in a stark white setting designed by Katrina Lindsay, flecked with scudding clouds and rippling water, and dotted with associates (Gawn Grainger is chief narrator and worry merchant) and choric matrons in black (sympathetic Liz Crowther and big-voiced mamma Sue Kelvin).
Good lighting by Ben Ormerod, and the lilting Greek music of Ilona Sekacz creates a world of innocence, yearning and escape that Onassis tramples through like a raging bull with still a soft spot for the paddock.
To 5 February (www.onassistheplay.com)