Aristo, Festival Theatre, Chichester

If you happen to be a conspiracy theorist with a taste for postmodern updates of Greek tragedy and if you don't believe that brevity is the soul of wit, then sitting through the two hours 45 minutes of Aristo will be like bingeing on ambrosia for you. The piece is intermittently fascinating for the rest of us, too, and would be even more so, if forced to shed some of its bagginess.

The title is the nickname of the Greek shipping tycoon Aristotle Onassis, whose enormities are captivatingly portrayed here by Robert Lindsay with the kind of ruthlessly self-centred charm that singes the souls of the suckers surrounding him. Based on the book Nemesis by Peter Evans, Martin Sherman's new play casts the protagonist's harassed financial assistants as a harbour bar-frequenting Greek chorus. The idea is that plutocrats such as Onassis are the latter-day equivalents of the ancient demi-gods who considered themselves excused from the obligations of humdrum morality but who were not exempt from the twists of vengeful fate.

Cleanly and clearly presented in Nancy Meckler's sleek, spare production, the play suggests that there were many reasons why Revenge should have stalked Onassis and eventually presented him with the corpse of his handsome, likeable son (attractively evoked by Joe Marsh), who was killed in a flying accident. Did Onassis have a deal with the Palestinians, paying for the murder of Bobby Kennedy in return for the immunity from hijacking of his airline? Was his grudge against Bobby K the result of CIA disinformation as well as Bobby's distaste for his projected marriage to Jackie K (wittily played by Elizabeth McGovern)? Did his trophy-hunting enslavement of Maria Callas (excellent Diana Quick) cause her to neglect, and so hasten the destruction, of her miraculous voice?

The play lunges between the focused and the hokey. It wryly admits with its brain-knotting lecture-explanations that there is a comic side to its alleged findings. But at other times you almost feel that you've been assigned to the role of stooge in a conscious, deadpan hoax. I very nearly lost patience with the piece during the bit when a female cleaner started singing about the death in a car crash of her own unglamorous son. To start invoking the rights of the common man at that late stage of this orgy of name-dropping felt (if I may coin a phrase) a bit rich.