Penny struggles with Leonard's confession that he kissed another woman as they prepare to get married in Las Vegas. Meanwhile, Sheldon doesn't know what to do after Amy pushes pause on their relationship.
Leonard confronts the woman he kissed on the North Sea in an attempt to set Penny's mind at ease. Meanwhile, Sheldon films a special episode of "Fun with Flags" after his breakup with Amy, and Bernadette feels guilty about withholding a secret from Penny.
Wil Wheaton interviews Sheldon for a Star Trek documentary where he reveals the ring and his plan to propose to Amy. Bernadette wants to start renovating the house and the topic of starting a family together with Howard is brought up.
On Thanksgiving, Sheldon and Amy try to spend time together as friends and go to an aquarium, Howard reluctantly agrees to volunteer at the soup kitchen with Bernadette, Raj and Emily, and Penny discovers that Leonard knows more about her than she thought.
Sheldon can't get a tune out of his head. He can't work out what song it is. Meanwhile, Amy is having Dave over to her's, but Bernadette is reluctant. Howard and Raj meet a fan of their band and Sheldon gives Amy an ultimatum.