Onassis portrays the last years of the life of the wealthy shipping magnate Aristotle Onassis, who after a notorious affair with Maria Callas, married Jacqueline Kennedy, widow of US President John F. Kennedy, in 1968.

A millionaire at 25, he had become one of the world's richest men, but it was the glamour of the women in his life which brought him real fame, causing him to pursue personal vendettas and amassing empires on an international scale.

Based in part on Peter Evans' book Nemesis, Onassis is an explosive account of one man's voracious appetite for sex, money and power.  The play depicts Onassis' complex interwoven relationships with women and his family, as well as his long-running feud with the Kennedy family and the American establishment.  With hints of Greek tragedy and hubris, it explores how those with great wealth and political influence live their lives detached from the moral code and realities of ordinary mortals.

Onassis is a revised version of the play which, under its former title Aristo, opened to critical acclaim at the Chichester Festival Theatre in 2008.