Barney gets Marshall back out on the singles market, but Barney keeps taking all the prospects from him. And Ted's convinced that Lily is back because she wants Marshall back, even though she says she's never been better.
Ted discovers that his parents are keeping a secret from him after his dad acts as Barney's wingman, and Marshall and Lily intentionally try to get each other sexually aroused.
Barney tells Ted that single women like architects. But will Ted use this useful tidbit of information to cheat on Robin after they have their first fight?
Lily gets introduced to Barney's bachelor pad when she needs a place to stay, and Marshall finds a unlikely new friend to join him for brunch, concerts and musicals.
Ted gets Lily a job at his firm, but she only makes trouble for Ted when he refuses to stand up to his boss. And Barney sleeps with Marshall's law school professor to help his grades, but she's less than impressed with his prowess.
The guys tell Marshall to stay away from his new date because she has "crazy eyes," but she couldn't be any crazier than Lily after she learns that Marshall's going out on his first new date.
The gang discovers that Robin's been hiding a huge secret, but they have no idea what it is. Marshall thinks she is married, and Barney thinks she was a porn star.
Lily takes away her Christmas display after she finds out that Ted called her a bad name while she was broken up with Marshall, and Barney is too sick for his Christmas plans.