Howard has noticed that Sheldon disappears for exactly twenty minutes every afternoon at exactly the same time without telling anyone where he's going or what he's doing. The twenty minutes is listed as free in his calendar. And when Howard and Raj ask him indirectly about that twenty minutes, he evades the question. So Howard and Raj go on a single minded mission to find out where he's going and what he's doing that is so secretive. They try to piece together the evidence they find, but will it lead them to an answer? Leonard isn't joining them in this quest since he's got his own mission. Penny has befriended Cole, a British exchange student in her History class who Leonard is certain is trying to hit on her. Although trusting her somewhat, jealous Leonard does whatever he can to stop Cole indirectly from being her friend (which he equates to hitting on her) so that Penny won't even be tempted. But Leonard himself may be tempted from who to him is an unlikely source.