WITH SPOILERS FROM LAST NIGHT “Mad Men” Episode 4 (technically), Season Five: Don Draper gets the flu and a fever, and dreams of cheating on new wife Meghan with one of his old flames, Andrea– a one night stand (or less) that occurred during his marriage to Betty. Is Don a sex addict long before such a thing existed? Maybe. In his fever dream he strangles Andrea and pushes her dead body under his bed. In “Mystery Date” we get the second dream sequence in a row this season, Last week, in “Tea Leaves,” Betty dreamed she was dead, and watched her kids, husband Henry and her mother in law eating breakfast in funereal black. Now Don dreams of having sex with this woman he runs into– the “mystery date.” Peggy has a mystery date, too, of a different nature–inviting home Dawn, Don’s new black secretary, when she needs a place to sleep. Figuring as a plot point is Richard Speck’s July 1966 massacre of Chicago nurses. Where “Tea Leaves” at least had fun with references to “Bewitched,” the Rolling Stones, and George Romney, “Mystery Date” has a grimness to it. It also serves to get rid of Joan’s annoying husband, Greg (Sam Page), who re-ups with the army in Vietnam. Joan throws him out. Also, the new copywriter, Michael Ginsburg (Ben Feldman), who everyone thinks is a “genius”–exhibits warming signs of disloyalty and ambition. He may be Trouble. “Tea Leaves” was an A, “Mystery Date” is a B for now, unless it turns out to mean more than we know right now.