Ryan leaves Newport to visit his mother, but before they meet he has a steamy encounter with her co-worker. Meanwhile, Seth is keeping secrets, and Taylor and Summer devise a foolproof plan to figure out what is going on with him. When their plan backfires, Summer is devastated. Julie Cooper visits a surprised Volchok and gives him some stern advice. Later, Marissa confronts Volchok's friends and saves a girl from an intense situation at a party. Meanwhile, Sandy puts an end to the trouble with Matt but leaves Kirsten at home alone.