Robin's musical past emerges again as the group learns of someone named Simon from Robin's past. Barney searches for more Robin Sparkles memorabilia.

Lily comes up with a perfect plan to break up the relationship between Barney and Robin when they have a rough patch, but she needs help from Robin's famous friend, Alan Thicke, in order to make it work.

Barney's discovery of a Canadian kids show called Space Teens, that Robin appeared on as Robin Sparkles, leads the gang to get her to reach out to her co-star, Jessica Glitter.

Barney uncovers the lost episode of Robin’s “Underneath the Tunes” as Robin Sparkles. Meanwhile, Marshall and Lily are concerned that Ted’s new girlfriend is a stalker.

Robin is dismayed when Barney wants to have their rehearsal dinner at a laser tag arena; Ted aggravates Lily by not following through with a promise.