Howard's half-brother comes to Pasadena to give a presentation on the ocean and invites the gang to it after he meets the rest of them.
Howard's half-brother Josh comes back to Pasadena and goes to Howard and Bernadette's house. He tells them to stay that he's in Pasadena because he's going to give a presentation on the ocean. He came with the train and decided to stay with Howard and Bernadette since Howard had read his e-mail that he would like to stay with his half-brother and half-sister-in-law. Josh is relieved and is also relieved that he's going to be a half-uncle.
The next day, Howard and Bernadette take Josh out for a little fun and they meet up with Raj, Emily, Stuart and Alex. Howard and Bernadette introduce Josh to them who are all surprised to find out who he is (except Raj who had met him already along with Howard and Bernadette) since no one knew Howard had a half-brother.
They all head off to Apartment 4A where Leonard, Sheldon, Penny and Amy are together talking and soon Bernadette, Raj, Emily, Stuart and Alex enter and greet everyone. Lenny and Shamy wonder where Howard is, but Bernadette tells them he'll be up in a minute. Howard and Josh soon arrive at the apartment and Amy is the first of the 4 (Her, Leonard, Sheldon and Penny) to see Josh. She asks who he is and Leonard, Sheldon and Penny see him too. Howard tells them who Josh is and they are so surprised as well since they didn't know about Howard having a half-brother.
They all have lunch and Josh invites all 10 of them to his oceanography presentation which is to be held at 3:00 p.m. at a hall in a small room filled with other students from Josh's class and 3 teachers the next day.
The next day, everyone goes to the hall and into the room where the presentation is being held and so, everyone grabs 10 chairs and sit down to watch.
At the end, everyone is very pleased with Josh's presentation and they all bring him back to 4A after the presentation. He immediately bonds with the guys over video games and comic books and the girls leave them to hang out together while they go to Apartment 4B to watch TV and talk. Everyone decides to have a sleepover in Apartment 4A, so everyone grabs pillows, blankets, sleeping bags and cushions and all go to sleep later that night in the living room.
Later, Josh needs to leave and with that, he says goodbye to all of his new friends and hopes to see them all again, but Sheldon assures him they will meet again since Josh is Howard's half-brother, Howard is a friend and Josh has bonded with the guys and been very friendly with the girls. And so, he takes off with Howard and Bernadette so he can return to Howard and Bernadette's house and get back to San Diego with his school group with the train.