Perfect Strangers (1986)

S6E10 Black Widow

Larry uncovers information suggesting that Mary Anne might be a serial killer, but Jennifer, who has known her forever, doubts his findings. Tension rises for Larry when he learns that Mary Anne wants to take Balki on a mountain climbing trip. His fears escalate further when Jennifer is unexpectedly called into work, leading him to believe that Mary Anne has harmed her. However, it all turns out to be a misunderstanding.