Barney has a stalker, a former scorned lover who is ensuring he never "scores" again. When the woman approaches Lily, warning her about Barney, the gang then composes a board of the women that Barney lied to and hurt the most, finally reaching a top 4, Barney and Lily set out to see if any of the 4 are his stalker. Failing, the gang sets up a scheme to catch his stalker in the act.
This episode was hilarious. Not only was the storyline incredibly interesting and funny, but it managed to reference "Ted Mosby: Architect" (a personal favourite episode from season 2!) The best bit was the plan to catch the stalker in the act at the end. Except for Ted really, the whole gang wasn't that subtle. For example Lily's attempt to hang by the jukebox and not draw attention to herself. Classic! Also Robin's laughing every time she lied and Marshall's freaking out about trying to act normal. A highly enjoyable episode! It also mention Barney's blog again, love it!