Veronica tries to help her new boyfriend Troy find his father's stolen car and turns to Weevil for assistance, but the situation becomes dangerous when she discovers that Logan and Troy's buddy Luke might have left more than a piata in the car after their night out in Tijuana.

While Keith has accepted that his wife is gone and begins dating school guidance counselor Rebecca James, Veronica continues to secretly investigate her mother's whereabouts, leading her to stumble on a secret Lianne Mars was keeping.

Veronica uncovers information that her fellow outcast Mac was switched at birth with a more affluent student, causing Veronica to examine her own questions about whom her real father may be. Meanwhile, a serial killer has resurfaced in Neptune forcing Sheriff Lamb to forge a reluctant, tense partnership with Keith. Later, Veronica flirts with a handsome young rookie at the sheriff's department to obtain more information on Lilly's murder.

While helping her classmate Mandy search for her missing Jack Russell terrier, Veronica stumbles onto a bigger mystery, which affects pets all over Neptune.

Meanwhile, tensions mount in the Echolls family as Trina tries to convince the now-retired Aaron to take a part in her new boyfriend's independent movie. Later, Weevil is arrested for breaking into the Kane residence and taking something from Lilly's room.

While dealing with her own feelings of jealousy regarding Duncan, Veronica helps a young woman who believes that her new fiancée is secretly after her fortune by sifting through his background and even posing as a sexy, available coed to entrap the guy.

After finding her mother's old permanent record at school, Veronica wonders how well she knew her mother at all, and decides to investigate her mother's school friends. Meanwhile, Trina takes the role of director in the school play, and while she has a confrontation with Kendall, Veronica has one with Celeste.

Overcome with guilt and frustration, Weevil asks Veronica for help to bring Felix's true killer to justice, but realizes he may have to take matters into his own hands.Meanwhile, Keith reviews a strange DVD that Woody receives in the mail, and relationship troubles brew between Wallace and Jane, and Mac and Cassidy.