When Sarah is attacked by a wild animal, it’s Natasha who saves her. So when Sarah gets an opportunity to make a switch, so that it isn't Natasha who gets handed into The City of Hope, she’s willing to do it. But when Natasha refuses, Sarah finds herself in a difficult position. Nathan knows that it’s his fault that Natasha has been taken, and he’s willing to do everything he can to save her, but does that include betraying her?