A detective begins a murder investigation but before the identity of the deceased is revealed, the story jumps back twenty years as the group at the funeral graduates from high school. Samantha is pregnant but not sure whether her boyfriend Craig is the father. One friend takes the fall for another's reckless driving.
Will finds life on the outside of prison difficult and a visit from his old cellmate makes it even more so. Samantha comes back from London after giving birth only to find out that because of a medical complication, she can't have another child.
Samantha has tracked down her missing baby, but the adoptive parents want nothing to do with her. Will and Craig continue to scuffle for Samantha's affection. Jenna's mother impacts her movie premiere. Aaron spends time in Seattle to try to get over Jenna. Detective Marjorino reveals that he has a personal investment in solving the murder case, that his stepfather was Edward Lawrence -- the man who died in the car accident.
Samantha is faced with a final choice between Will and Craig. Detective Marjorino learns the truth about who was behind the wheel that fateful night.
Carla continues a relationship with Paul. Craig tries to keep his company afloat with his father out of the picture as well as keep his marriage to Samantha going. Will has enlisted in the military and prepares to go to Kuwait. It's revealed that Samantha is the friend murdered at the reunion.
Sam tries to figure out the source of the mysterious bruises on Carla. Sam confronts Craig with the truth about Amy. Aaron is lured away from Craig's business by an Internet company. Will comes back from the Gulf War haunted by the death of a compatriot. Marjorino follows up a lead in the investigation revealed in an interview with one of the friends.
The friends come together for Thanksgiving in 1992. Rachel, who attends with Aaron, has been seeing Craig on the side. Things immediately seem off between Jenna and her movie star man.
Will and Craig reflect on 1993 while visiting Samantha's grave. Samantha's 25th birthday is weighed upon by the death of one of the ER patients. Craig tries to figure out whether he wants to pursue a career in politics. Aaron and Carla's chance to go out on a date is ruined when a woman approaches Aaron with his child.
In 1994, Carla's new boyfriend Peter mingles with the gang. Craig tries to win a campaign despite his infidelity. In the present, Marjorino Rachel and join forces to potentially bring down Craig. Marjorino is struck down by a car.