Meet Veronica Mars. Your typical high school student and private eye. A year ago, Veronica's best friend Lilly was murdered. Her father, Keith, then the town sheriff, accused Lilly's billionaire father of the murder. When another man confessed, Keith was booted from office. All of Veronica's friends stopped talking to her, and her mother left town. But as Veronica starts her junior year of high school, it becomes clear that nothing about her life is what it seems.
When Weevil's grandmother is arrested for credit card fraud, Veronica and Wallace reluctantly help the investigation to clear her name. Meanwhile, Logan's new girlfriend, Caitlin Ford, joins the 09ers in making Veronica's life difficult, while a new arrival in town, Troy Vandegraff, tries to get to know her better.
Veronica tries to help a classmate track down his long lost father, but with very little to go on, she finds the task more daunting than she thought. Meanwhile, Keith meets with school guidance counselor Rebecca James to discuss Veronica's feelings about Lilly's murder.
In an attempt to help out Wallace win over a potential girlfriend, Veronica takes on the case of tracking down an Internet fraud ring, which leads her to an underground gaming community. Meanwhile, Logan agrees to assemble a video of Lilly to mark the one-year anniversary of her death, and Troy becomes closer to Veronica.
After a night in Tijuana, Troy finds himself in a tough situation when his car is stolen and turns to Veronica for help. But what she finds changes her relationship with him. Meanwhile, Keith and Rebecca begin dating against Veronica's wishes, and Veronica makes another shocking discovery about her mother.
The tension between the 09ers and non-09ers comes to a head when the school elections appear to be rigged. Veronica helps Wanda, the underdog, campaign to beat Duncan, despite her feelings for him. Meanwhile, Logan clashes with his father, movie star Aaron Echolls, when he is caught in the press engaging in unruly behavior.
Veronica becomes suspicious when a young pregnant woman who lives in their apartment complex suddenly disappears; fearing the worst, Keith steps in to help his daughter investigate this case for the girl's estranged parents. Meanwhile, Logan and Weevil get thrown into detention together after arguing with a teacher, leading the rivals to discover some surprising things in common. Later, while working on an alumni photo project in her journalism class, Veronica is shocked to discover that her mother and Jake Kane were high-school sweethearts.
A purity test being passed around Neptune High leaves Veronica's friend Meg humiliated, which leads Veronica to uncover who would want to ruin the reputation of the nicest girl in school. Meanwhile, Keith helps Wallace's mom with a tenant who refuses to leave, and Veronica has a shocking meeting with Lilly's confessed killer.
Against her father's wishes, Veronica infiltrates what she believes to be a cult in order to investigate a classmate's sudden change in personality. But after meeting the people in the cult, she begins feel like she is making a mistake. Meanwhile, her investigations into Abel Koontz's claims about her family continue.
A holiday poker game at Logan's house gets nasty when Weevil's winnings disappear, leaving Veronica to determine the guilty party before Weevil finds his own way of getting the money back. Meanwhile, Keith helps Lynn Echolls find out who is sending threatening messages to her husband, Aaron, before their big Christmas party.
After setting up a new business helping classmates dig up dirt on their parents, Veronica uncovers a huge revelation about her friend Mac, which leaves her wondering if some things about your family are best left unknown. Meanwhile, Keith must team up with Sheriff Lamb to track down a serial killer in Neptune.
Veronica finds herself the target of a set-up when a secret underground society within Neptune High begins planting evidence to get her in trouble. Meanwhile, Veronica learns new information about Lilly's murder by eavesdropping on private conversations, and Aaron Echolls becomes concerned about his wife.
After a wealthy music producer's daughter goes missing, Veronica almost bites off more than she can chew in her attempt to find her old friend. Meanwhile, Logan finds it difficult to show the proper emotions at his mother's wake.
When a girl in school accuses Veronica's favorite teacher of sexual harassment, Veronica finds herself pitted against her father, who is hired by the girl's family to get him fired. Meanwhile, Logan enlists Veronica's help to track down his mother, who he believes is still alive.
As Valentine's Day approaches, Veronica finds herself working as a love detective, tracking down Meg's secret admirer and helping a Russian woman find her missing fiancé, both with unexpected results. Meanwhile, Logan's family troubles continue when he stakes out a hotel that he believes is hiding his mother.
Veronica is shocked when Van Clemmons hires her to track down the missing school mascot, Polly the Parrot, but is distracted by memories of her recent reunion with her mother. Meanwhile, Veronica digs deeper into the Lilly Kane case, using her new relationship to gain access to private information.
Veronica investigates who at school is doing everything possible to distract the valedictorian front runner from studying and wreck her grades in an obvious attempt to sabotage her. Meanwhile, an unsavory, rival private investigator makes Keith a business offer. Later, Veronica pursues a risky lead that could discredit Abel Koontz's confession, as Logan stumbles onto her detailed files on everyone connected to Lilly's murder.
After several fire drills and bomb threats rock Neptune High, Veronica looks to new student Ben as a possible suspect. Meanwhile, Veronica and Wallace are shocked to discover that their parents have been secretly dating, and Duncan finds out that Veronica has been spying on him.
When awkward classmate Mandy asks Veronica to help her find her missing dog, a much larger scheme is exposed as they follow the trail. Meanwhile, Logan's sister Trina begs her father to play a role in her new boyfriend's movie, while Logan suspects that Trina is hiding something.
Veronica helps her friend Carmen plot revenge on her clingy boyfriend, after he releases a scandalous tape of her over the Internet. Meanwhile, Keith decides to track down the missing Duncan in exchange for the huge Kane reward.
After obtaining a shocking new piece of information, Veronica is determined to get to the bottom of what happened the night she was drugged and raped, even if it means piecing together the fuzzy stories of every 09er at Neptune High. Meanwhile, Aaron throws a party for Logan, but inadvertently throws a wrench into Logan and Veronica's secret relationship.
In the shocking, action-packed first season finale, a determined Veronica must betray someone she cares deeply about in order to solve the mystery of who murdered her best friend Lilly, but what she discovers puts her life in serious danger. Meanwhile, Jake Kane asks Duncan if he really wants to know what happened on the night Lilly died, and Keith awaits the results of a paternity test.