Marcia Rodd guest stars as a woman named Marilyn Sanders, who unexpectedly shows up one night at the Bunker doorstep. Insisting that Mike is father of her son (Steve Manley), Marilyn leaves the kid with the Bunkers and disappears as quickly as she came. Now Mike must do a lot of soul-searching (and mental backtracking), while the rest of the family struggles vainly to cope with this latest bombshell. Written by Warren Murray, "Mike's Mysterious Son" first aired on January 22, 1972. ~ Hal Erickson, Rovi