Ep 16. Sandcastles in the Sand

Ted bumps into his old high school girlfriend, Tracy, and the two decide to catch up over dinner. As they reminisce about their past relationship, Ted realizes that he's never really gotten over her and begins to fantasize about what could have been. Meanwhile, Robin discovers an old music video she starred in as a teenager called "Sandcastles in the Sand" and becomes obsessed with reliving her glory days. With the help of Lily and Barney, Robin sets out to reunite with Simon, her ex-boyfriend from the video, and recreate their cheesy beach romance. As their respective trips down memory lane unfold, Ted and Robin both realize that sometimes the past is better left in the past. Meanwhile, Barney struggles to come to terms with his own feelings about ex-girlfriend Shannon, who recently got engaged to someone else. Despite his attempts to ignore the news, Barney eventually confronts his emotions head-on and decides to take a big step forward in his own love life.