Kirsten's unemployed sister, Hailey (recurring guest star Amanda Righetti), moves in with the Cohens and disrupts the entire family when she behaves as the houseguest from hell.vanytime soon. Desiring some time alone with his wife, Sandy urges Kirsten to resolve the problem with her sister. When Kirsten can't confront Hailey, Sandy angrily tells Hailey that everyone is tired of tolerating her rude behavior. Meanwhile, Seth and Anna (recurring guest star Samaire Armstrong) struggle with telling Summer the truth that they are now a couple. Ryan feels jealous about Marissa's new friend, Oliver (recurring guest star Taylor Handley), a neglected, drug-abusing teen she met in therapy who always seems to show up when Ryan wants some privacy with Marissa. Later, Ryan helps Oliver by asking Sandy to intervene when Oliver is arrested for trying to buy drugs from an undercover cop.