Ted tries to keep his irresponsible sister from hooking up with Barney during her trip to New York, and Robin starts hanging out with Marshall at a bar for Minnesotans, not telling them that she's really Canadian.

Barney tries his best hoping to convince Robin into becoming an American citizen, while Ted and Marshall's road trip takes an unexpected turn for the worst when Marshall invites Lily to come along.

When Zoey enrolls in Ted's class, she manipulates his students into taking her side in the fight to save the building being torn down to make room for his project. Meanwhile, Marshall and Lily spot Robin marching in the Halloween parade of shame.

When Ted goes on a date without researching the girl on the Internet, the gang interferes, showing Kevin that they are too into each other's business. Meanwhile, Lily and Marshall come to terms with finding out the sex of their baby.

Although Ted is happy with living alone at his new apartment, Barney tries to convince him about going out every night. Lily has a naughty dream about someone other than Marshall. Robin finally starts her stint as a news anchor at World Wide News.

When Lily and Marshall have trouble finding a nanny, they learn it’s because of an elaborate scheme Barney came up with to meet girls. Meanwhile, Robin and Ted butt heads over who has a more serious relationship.

When The Captain asks Lily to move to Rome for a year as his art consultant, she fears that Marshall will resent her. Meanwhile, Ted and Barney become obsessed with a girl who is hiding her amazing body under a puffy coat.