Stella says "yes" to Ted's proposal. Robin sets out to Japan for a new job, but soon resigns and returns to New York to attend Ted's wedding. Stella says goodbye to Ted at the altar to get back together with the father of her daughter, Tony. Barney struggles with his feelings for Robin as his company assigns him to work in management team of a new acquisition, Goliath National Bank. Robin finds out about Barney's feelings for her, which she carefully reciprocates. Meanwhile, Ted thinks he is done being an architect and finally decides to takes on the job as architecture teacher. Can he find his true love around the classes?