It's a two-man show, with Pacino playing a down-and-out gambler, dreamer and liar named Eerie, who spends a long, exhausted night talking to the night clerk at the flophouse he stays at. That clerk was played by Paul Benedict. Mr. Benedict passed away on Monday. He was 70 years old.
Though I did once almost literally run into Pacino in the halls (that's another story), I actually met and spoke with Paul a few times, and he was a kind and funny man. He was amazing in the paly, delivering wonderfully funny stream of conciousness monologues and more than standing up to the powerhouse that is Pacino.
Of course, Benedict was most famous for his wonderful portrayal of Mr. Bentley, the neighbour, on The Jeffersons. He also was the first director of the classic play Frankie and Johnny in the Claire de Lune. The LA Times has a nice obit here.
Rest in Peace, Paul, I'm glad to have met you.