Amy and Sheldon are having their Annual State of Relationship Summit. It is the time to analyse their relationship and go through the items listed on their relationship agreement. Amy complains that Sheldon has yet to give her a pet-name, and names such as Golem and Flaky are unacceptable. The last item on the list is Valentine's Day, which according to Sheldon is akin to saving the worst for the last. Amy has made a weekend plan to celebrate the day -- bed and breakfast arrangement at Napa Valley. Sheldon does not share Amy's enthusiasm, and expresses his hate for the idea. He believes that their relationship is just three years old and people might talk if they share the room. He has some more complaints but Amy has come fully prepared. She tells him that Bernadette and Howard are going to join them. The clincher is the Valentine Day's dinner on a fully functional vintage train. Sheldon cannot refuse anything train related.

Penny and Leonard are not joining the two couples. Penny says they intend to spend a quiet weekend at home, while Leonard says that it is not a good idea to take Penny to the place from where wine comes from. Raj plans to spend his Valentine night looking at the stars from the telescope lab. He asks Leonard and Penny to watch cinnamon.

On the vintage locomotive train, Sheldon says it aloud that it is going to be the best Valentine Day, ever. Sheldon, Amy, Howard and Bernadette are having their Valentine Day dinner. Sheldon asks a waiter what kind of coupler is being used by the vintage train car. Waiter has no answer to do that. However, one of the co-passengers, Eric, provides the answer. Sheldon moves to Eric's table. The two bond over their common-love for trains. Amy is frustrated.

At Apartment 4A, Leonard is watching cinnamon when Penny walks in with a box of chocolate and flowers. Leonard tells Penny that they can do it anywhere as there is no one in the apartment. They can do it at Sheldon's spot. Penny, however, does not approve of that. They go to Leonard's room. When they come out of the room, Penny sees that cinnamon has eaten all the chocolates. Leonard and Penny take cinnamon to a vet, as chocolates can make dogs sick. Raj arrives at the clinic and is furious that the couple failed to take care of his dog. Leonard comes to know that chocolates came free with a full tank of gas, while he had given Penny the expensive Lakers tickets. Raj accuses Leonard and Penny of trying to kill his dog. To the beautiful, lady vet, Raj tells that he is the dog's owner, father and soul-mate. He tells the Vet to sing Katy Perry if cinnamon is scared during her fluid session. The vet later tells him that she did sing Katy Perry to cinnamon. At his home, Raj discovers that the vet, Yvette, has given him her phone number.

At the vintage locomotive train, Amy's frustration keeps rising, as Sheldon gets busy talking to his new friend. Bernadette decides to do something about it. She sternly tells Sheldon to get back to his table and be with Amy, reminding him that he is on a Valentine dinner with his girl-friend. Sheldon realises that he has been insensitive, but asks his new friend to join him at his table. The two indulge in a train trivia session. Sheldon wears an excited look, while Amy looks dejected. Sheldon and Eric visit the engine room.

When Sheldon comes back from the engine room, he tells Amy that the he and the conductor have the same pocket watch. Also, Amy gets to know that the conductor will come down to the bed and breakfast and play banjo for them. Amy decides to have a talk with Sheldon, and asks Eric to leave. Howard and Bernadette also excuse themselves. Amy is bordering rude in her behaviour. She tells Sheldon that they were supposed to have a Valentine weekend. Sheldon reminds Amy that she had told him that the trip is going to be something that both will enjoy. Sheldon questions whether she meant that, or was just trying to trick him. Amy tells him that she deserves romance. An agitated Sheldon says "if you want romance, let's have romance" and takes a sip of wine and gazes into Amy's eyes. He kisses Amy, saying kissing is romantic. Sheldon feels something and becomes sombre. Amy says "that [kissing] was nice." Sheldon takes Amy with him to the engine room. The conductor had promised to show Sheldon how to bring a train through the crossing.

Back home, Sheldon tells Leonard that the trip was wonderful, as he made a new friend, kissed Amy on the lips, and the conductor played the banjo for him. Leonard questions him all these things were equal to him. To Sheldon, it never occurred to pick a favourite and to do that he would need additional data. Leonard guesses Sheldon is thinking of taking things further with Amy. Sheldon pours cold water on that guess when he mentions listening to other nine-finger banjo players, which is his idea of collecting additional data.