Ep 5. Architect of Destruction

Ted hires a new architecture professor to teach at Columbia University, whom he idolizes. However, when the gang meets him, they quickly find out that he is quite difficult to handle. Marshall and Lily, who have just moved into their new apartment, are feeling unsettled by a constant tapping noise they can't identify. Barney becomes obsessed with trying to figure out who the mysterious woman is he saw on the subway platform. Robin finally confronts her feelings for Ted but it backfires. Meanwhile, Ted learns some hard lessons from his new boss.