Ted's parents visit New York for their anniversary and he learns a family secret. Robin worries that they won't like her. Lily and Marshall try to adjust to the new format of their relationship now that they are no longer together.

Ted almost ruins Christmas for everyone when, still carrying around anger toward Lily, he calls her a horribly disgusting name. Robin tends to Barney while he has a cold.

When Ted attends his mother's wedding, he is extremely disturbed by her overly affectionate relationship with her fiancé, which forces him to think about his own life and make an impulsive decision.

When Ted is faced with an important decision that might affect his future with Zoey, the gang expresses their true feelings about her.

The gang begins to realize their romantic partner reminds them of one of their parents. Meanwhile, Barney and Nora's planned romantic evening is ruined by a string of bad events.

When Robin and Loretta's conflict escalates, Barney is caught in the middle. Meanwhile, Marshall and Daphne deal with a stowaway on their road trip, and Ted and Cassie try to enjoy a trip to a lighthouse.

Robin and Ted reminisce about past relationships as they search for a drunken Barney on the day of the wedding; Lily and Marshall come to a resolution; Barney befriends two men who are eager to meet women.