Immediately upon the guys' arrival back from the three month long Arctic expedition, Leonard, Howard and Raj make a confession to Sheldon about their participation in Sheldon's research at the North Pole. This confession threatens Sheldon's research, his job and his friendship with the threesome. Sheldon's mother may at least have the answer to fixing the friendship. Meanwhile, Penny is really happy to see Leonard home. Leonard is equally happy to be home to see Penny. But every time they are about ready to embark on their first sexual encounter with each other, something always seems to get in the way.