The huge number of comments posted here is testimony to what a great episode this is.

It's worth adding that Paul Hecht grabs this show and runs away with it.  The cheerful malevolence with which he makes his plans.  The cool, calm professionalism with which he makes his proposition to Adams's character.  The utter lack of any morals except for those he seeks to play upon in his victim's conscience.  Just terrific work by Hecht, one of the best male actors (right next to Norman Rose!) on CBSRMT.

Well worth a second listen and a third!