Travelling to Long Island Robin and Barney come across a startling family discovery and Lily doubts Ted really has let go of Robin.
Robin worries about how Barney will take the news that his brother is getting a divorce. Meanwhile Marshall tries everything he can to get to the wedding in time.
When Lily discovers Ted's list of things he wants to do in New York before he moves for Chicago, she becomes frustrated that she is the only person who knows about his plans. Meanwhile, Robin and Barney realize they have very little time together before their relatives arrive for their wedding.
While Barney works through his anger at Ted after finding out he still has feelings for Robin, Marshall Skypes in to act as a judge and help settle their dispute. Meanwhile, Lily realizes she is Robin's only girlfriend.
When Barney is forced to pick sides in a fight between Robin and his mother, Lily coaches him on how not to ruin his relationship. Meanwhile, Ted and Marshall get into a dispute over wedding gifts and thank-you notes
When Ted finds himself with three prospects to be his date for the wedding weekend, he chooses poorly. Meanwhile, Barney and Robin have a confrontation with their minister, and Marshall learns more about his driving companion, Daphne
When Daphne sends a troubling text message to Lily, Marshall enlists the gang's help to remove the message while enforcing the "No Questions Asked" rule
When Robin and Loretta's conflict escalates, Barney is caught in the middle. Meanwhile, Marshall and Daphne deal with a stowaway on their road trip, and Ted and Cassie try to enjoy a trip to a lighthouse
In a flashback episode, the gang ponders the future of the Ted, Robin and Barney love triangle. Meanwhile, Barney accepts a series of challenges from Lily and Robin
When Barney's father arrives at the hotel, Barney devises a plan that makes Robin very nervous. Meanwhile, Ted is convinced someone framed him by messing up a wedding-related duty
Marshall tries to get Marvin to sleep by reciting three rhyming bedtime tales about his friends as they wind down their epic cross-country journey.
Barney becomes fixated on having his rehearsal dinner at a laser tag arena, much to Robin's dismay. Meanwhile, Ted doesn't come through on a promise, which aggravates Lily
The gang encounters a guy at the wedding who intentionally stirs up trouble among them, and Marshall finally arrives at the Farhampton Inn