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