Part of the excellent Brits Off Broadway series, David Rudkin's play pries the lid off Hitchcock's psyche, the better to peer in and consider the ghosts and ordeals that Mr. Rudkin sees as the fuel of his art. Some of it is schematic, some poetic and some compellingly theatrical. A strength of "Lovesong" is its often deft use of theater to evoke another art - movies - which, in the case of the Hitchcock classics, have taken up residence in our heads, as this play neatly demonstrates.