Houdini & Doyle (2016)

S2E22 Something Blue

Title: A Touch of Blue Plot: As Marshall and Lily celebrate their wedding reception, the festivities take a lively turn. Robin attempts to share a heartfelt story but is continually cut off by the chaos around her. Meanwhile, Barney is on a mission to uncover the hidden truth behind Ted and Robin's mystery, determined to piece together the puzzle of their past.