Taylor ruins Seth's night when she throws a Harbour School event that keeps Summer at a distance; Marissa's new friendship at the public school worries Summer so she enlists Ryan's help.

As the seniors prepare their college applications, Marissa is unable to make a decision.

Charlie is sceptical and nervous when a girl from his past reveals that he is the father of their child.

Matt, Sandy's Newport Group partner, goes above and beyond the call of duty.

Marissa adjusts to life in her new surroundings and makes some new friends at Newport Union, Ryan wonders how their separation will affect their relationship, and Seth's feud with Dean Hess lands Summer in trouble.

Chaos reigns in the Cohen kitchen as Sandy, Ryan and Seth continue to cope with Kirsten's rehab; Sandy encourages Kirsten to come home to her family, but Kirsten's attachment to Charlotte raises concern in Sandy.

Although they are finally happy with each other, Marissa and Ryan are forced to stay apart by their parents. Elsewhere, Dean Hess pressures Seth and Summer into showing their Harbour School spirit, which leads them to devise a covert plan.

Kaitlin tries to get closer to her family after returning from boarding school.

Charlotte makes Julie an offer she cannot refuse.

After Sadie and Ryan go on a road trip, it could signal the end of Ryan and Marissa's relationship.

The senior prom is in full swing, with Taylor on a high and Summer falling flat with her date.

Ryan visits his mother and ends up having a steamy encounter with her co-worker. Meanwhile, Summer is devastated when the plan to figure out Seth's secret backfires.

A rift grows between Ryan and Sadie, while Taylor tries to solve Seth and Summer's problem.

The kids discover who has been accepted into college, and who hasn't.

The gang contemplate the year, and their futures, as the end of senior year arrives.

When Zoe makes an important decision, Wade tries to take care of everything before the baby is born; Lavon determines to make things right with Lemon; AnnaBeth and George are faced with a choice.

The team looks into a murder case of a six-year-old orphan from 1958. They discover that his true parents may hold the key to solving his murder.

Drama turns to Eric for help in his search for a job; Ari chases a new venture with the NFL; Turtle accuses ex-employee Alex of stealing company money.

Eric offers to take Sloan on a platonic date to the premiere of Vince's new movie; Ari arranges a meeting between Mrs Ari and Andrew's wife, and demands that Lloyd go on a diet; Turtle hits the red carpet with Jamie-Lynn Sigler.

Eric finds himself caught between Sloan and Ashley; Andrew's behaviour threatens a big deal; Vince and the boys decide that further steps are necessary to ensure their safety.