A mysterious and ominously silent stranger comes into Cheers, putting everyone on edge wondering who he is and what he wants. It turns out that the stranger's visit was arranged by Diane (Shelley Long), who is conducting an experiment on paranoid behavior. The gang calmly lets Diane know that they intend to even the score, very soon -- whereupon she becomes a dictionary definition of galloping paranoia. ~ Hal Erickson, Rovi