Episode 98 of "Malcolm in the Middle"
s05e13 Lois' Sister
Title: Lois' Sister
Original Air Date: 02/22/2004 on Fox
Director: David D'Ovidio
Writer: Gary Murphy
Guest Stars: Kevin Cooney (Dr. Dumont), Jasmine Di Angelo (Brittany), Abigail Mavity (Meagan), Josh Jacobson (Matt), Heather McPhaul (Trish), Laurie Metcalf (Susan), Tianna Danielle Kenney (Buttercup #2), Montana Tsai (Buttercup #4), Chanel Gaines (Buttercup #6), Hayley Erin (Buttercup #1), Gracie Markland (Buttercup #5), Alyssa Monka (Buttercup #3), Kate Lang Johnson (Katie)
Plot Outline:
In the milestone 100th episode, "Lois' Sister," Lois' younger sister, Susan (Laurie Metcalf), pays the family a visit and brings with her expensive gifts for the boys, biting remarks for Lois and a cold shoulder for Hal – whom she has never forgiven for dumping her for Lois. Lois and Susan's competitive relationship takes a turn for the worse when Susan gives Malcolm and Reese her prize '65 Mustang convertible. But when Lois discovers that Susan needs a kidney transplant, she puts her anger aside and offers to donate her kidney to Susan, which Susan only sees as the perfect opportunity for Lois to one-up her.
