When Ted sees the "Slutty Pumpkin" costume in a storefront window, he is able to track down the woman he met ten years ago at a Halloween party. Although Naomi is perfect on paper for Ted, he feels no chemistry, nor does she, despite their best efforts. Meanwhile, Lily's grandparents give Marshall and Lily the key, and ownership to their house in the suburbs. Lily, who has always hated the suburbs, wants the house because she has "Pregnancy Brain," and her hormones are causing her to act irrationally. Although Marshall wants to move, he doesn't want to take advantage of her irrational thoughts, and they need to wait until the baby is born before they make any big decisions. In addition, Robin discovers that Barney is a quarter Canadian and endlessly teases him.