Justin, Penny's rock musician friend from Omaha, is coming to Los Angeles looking for work in the industry. Penny is letting him sleep on her couch for a few weeks. This offer doesn't sit well with a jealous Leonard, who learns that Justin and Penny did at one point "go out". Beyond the actual standoff between Leonard and Penny, their fight affects Howard and Raj, who take opposing sides, and Sheldon, who just doesn't like fights. As he feels this fighting is affecting him more than anybody else, Sheldon takes matters into his own hands. But will Sheldon end up hurting them and himself more than he helps?