As with the play, the movie focuses on real estate salesmen. Shelley Levene (Jack Lemmon) is the old-timer who's getting past his prime. He hasn't had a good sale in a long time, his daughter's in the hospital, and he doesn't have much left in his banking account. On the other end is Ricky Roma (Al Pacino), who's doing well enough that he can skip a company meeting to try and sell property to new client James Lingk (Jonathan Pryce). In between are Dave Moss (Ed Harris) and George Aaronow (Alan Arkin), who aren't in as desperate straits as Shelley is, but are still struggling. At the company meeting everyone but Ricky attends, Blake (Alec Baldwin), an emissary from the bosses (Mitch & Murray, who are never seen), drops a bombshell on the others; the sales contest they're having is also a war of attrition on the salesmen - 1st prize is a Cadillac, 2nd prize is a set of steak knives, 3rd prize is a pink slip.
Each of them react in their own way. Shelley tries to buy the good leads (likely prospects) from Williamson (Kevin Spacey), the manager, but Williamson is unmoved. Dave and George bitch about not having access to the good leads (known as Glengarry leads), reminisce about the days when they had good leads like Glen Ross leads to sell, and Moss floats the idea of robbing the office of the good leads. The next day, everyone comes to work to find the office has been robbed of the good leads. Ricky, in the meantime, finds out the next day that his sure thing sale (which he knows will get him the Cadillac) may not be a sure thing after all.