Season 1[]
A year after her friend Alison disappeared, Spencer reunites with her old friends after a mysterious text reveals that someone knows her secrets. She is with her friends when the police discover what they believe to be Alison's body. At her funeral, the girls discover that they all received messages from "A". Meanwhile, Spencer finds herself attracted to her sisters' fiancé, Wren Kingston and they kiss.
After, discovering Jenna Marshall returned to Rosewood, the Liars fear that "The Jenna Thing" will be revealed. Later, she hangs out with Wren and Melissa and continues her flirtatious journey with Wren. Afterwards, Wren hangs out in Spencer's room where they make out not knowing Melissa is watching them. The next day, Spencer notices Jenna texting while on a run and suspects her of being A.
While wondering if erecting a memorial to Alison is right or wrong, she is at odds with her family over her Wren's affair. They don't believe her when she tries explain that Wren kissed her first. She later meets him in Philadelphia and leaves after he comments that he met the wrong sister. Later, she steals Melissa's old A-grade paper from Russian History and makes it her own. The next day, the girls reconvene in the woods to memorialize Alison in the shed they used to play in but decide to do it in a more public place.
Going along with their new plan, the girls map out the details of Alison's new memorial park bench. Spencer then comes up with the idea of "A-proofing." In the hallway at school, Mr. Sheldrake, Spencer's Russian history teacher, lets Spencer know that her essay was excellent and that he submitted it to an essay contest called 'The Golden Orchid. Later she encounters a drunk Wren and helps back to his motel room. Hanna discovers this and Spencer agrees with her friend that they are both in over their heads.
Still reeling from the haunting message scrawled across Spencer's vanity, the next morning the girls discover an additional, even spookier message from "A" – this one in the form of a video of the girls the previous night that was clearly recording them from inside Spencer’s closet. At school, Mr. Sheldrake walks over congratulating Spencer on her win' in the Golden Orchid competition. This encourages her father to invite Spencer to play double tennis where she meets Alex Santiago and the two start dating.
There's No Place Like Homecoming
Spencer urges Hanna to try and steal Jenna’s file from the psychiatrist’s office believing it to hold the key to identity of "A." Meanwhile she decides to take Alex to the homecoming dance. However, Melissa finds out about the stolen essay and attempts to ruin her night. She all but ignores Alex in order to see through with her plan to find A and Alex leaves in frustration.
The next day, Spencer tries to repair her burgeoning relationship with Alex, who’s now been reduced to kitchen duty at the Hastings’ country club. He's willing as long as Spencer gives him full control over the evening. When Spencer hears that Alex has canceled their date to work at the club, she finds him working overtime. She helps him with his kitchen chores in order to spend time with him. After a fight, they decide to move past it and slow dance where the two of them kissing deeply.
Please, Do Talk About Me When I'm Gone
In her room, Spencer looks at Alison's name bracelet for inspiration in writing her speech for Alison's memorial and thinks about Jenna. Spencer receives a text from "A" threatening her to do the memorial right. In the library, Spencer corners Jenna to try to feel out what Jenna is thinking in volunteering a speech for Alison's upcoming memorial. She warns Jenna not to make a debacle out of the solemn ceremony for her friend. Later, she speaks to Jason DiLaurentis and learns that Alison attempted to frame her for the Jenna Thing in case she tried to tell the truth. At the memorial, she sees Ian, Melissa’s ex, but even more surprised when Jenna takes the stage and says kind things about Alison.
Spencer, Aria, and Hanna study for the SAT while a storm brews in Rosewood. She confides in Hanna that she's afraid to show Alex to her family. after being cornered with her friends by Det. Wilden, her mother chastises Wilden. Spencer learns that Veronica is quite a fan of Alex and approves her daughter dating him.
Spencer remembers back when Ian flirted with her and getting called out by Alison. At the police station, Agent Cooper an FBI representative shows them footage of Alison talking to someone the day she died. At Mona's party, Spencer and Emily find a clue, a tree with Ali's name on it. They also see Ian's name which means they were dating. After receiving a text from Hanna, they head towad her direction only to see her get run over by "A".
At the hospital they call their parents. Hanna's mom comes over to tell them that Hanna has a broken leg, but is going to be okay. When Hanna say "A" is Noel Kahn and finds out Aria's affair with Ezra Fitz. While looking for the tree with "Alison + Ian" carved on it, she and Aria discover it chopped down. Later, Spencer is taken aback when Melissa reveals that her and Ian eloped.
The girls wheel their helpless friend Hanna back into her home. Spencer bought some stickers to cover up the "A" message on Hanna's cast. At Hanna's welcome home party, Spencer finds Alex outside, and he's all upset. Apparently, someone submitted his application for the tennis summit. He accuses Spencer of lying when she denies that she wasn't okay with Alex's decision to work instead. Since he only told Spencer about it, Alex breaks up with because he thinks Spencer went behind his back. She gets a text where "A" confesses their part in the break up.
Spencer sneaks downstairs while Melissa and Ian whisper ominously about something wonders why the two got married in the first place. She eventually discovers that Ian and Melissa wee at Hilton Head the same weekend as Alison before she died. Eventually, Melissa tells her the reason they were at Hilton Head was because they were trying to get pregnant. Later, "A" sends them an expanded video where Alison is supposedly murdered by Ian.
At school, the girls help decorate for the school's upcoming dance-a-thon, but take a break to discuss whether they should turn the video into the police. When Spencer's laptop goes missing, the girls think he stole it. She swipes his keys to his office only to be caught by Caleb Rivers and had to pay him off to keep him quiet. At Spencer's house, Spencer's laptop has mysteriously reappeared on the coffee table under some newspapers with the incriminating video erased and a photo of Alison the night she disappeared in its stead.
If At First You Don't Succeed, Lie, Lie Again
Spencer goes to seek out Jason DiLaurentis. He reveals that he is in Rosewood "taking care of family business". Later, Jason drops by Spencer's house to tell her that the picture was determined to be legit. Also, as it was taken from the point of view from the DiLaurentis home. It is very possible that Jason was the one snapping the photograph, but he doesn't remember. Later in her room, Spencer sits on her bed, reflecting on the picture of Alison the night she disappeared. She then flashes back to that night. Spencer had been arguing with Alison about not wanting to reveal that she had kissed Ian. She says that it was HER shadow in the picture with Alison. She had gone after Ali after the two had a fight. Spencer admits that the reason she had never told the girls thus far was because she had felt responsible for wishing Alison dead.
At the Cavanaugh home, Spencer stoops to pick up the mail. They start discussing the evidence from the day Alison disappeared. Suddenly, Toby hears someone (Jenna) shut a window and whispers to Spencer that he isn't supposed to be talking about this. He gives her the slip, thanking her for the book. Spencer returns to Toby's home and is nonplussed when he tells her to leave with barely any explanation. He hands her the French textbook and close. Spencer suddenly understands why Toby had been so secretive before, with the possibility of Jenna being so close.
In Spencer's room, the girls discuss the strangeness of Melissa's rapid change in life plans. They use a website to decipher the three letters of the Braille message: B-A-D. Spencer, upset about the message Toby gave her, goes to his house to confront him. He tells her she is reading it wrong and to come back Saturday morning when Jenna will be away at her flute lesson. As Toby walks away, Spencer gets a text from "A" warning her that Jenna will be pissed. She goes through Jenna's room to look for clues only to have Toby warn her not to; Jenna remembers exactly where she places things and will know if things are touched. After his anklet is taken off, Spencer offers Toby a ride to the station, and he accepts, leaving Jenna rebuffed when he turns down her ride in a taxi with him.
The next morning, Spencer has a dream that she is walking through her house at night. She hears a baby cry and descends the stairs into the living room, where a baby is lying in a bassinet. As she approaches the crib, someone sneaks up on her from behind and covers her mouth with his hand. She wakes up and begins to suspect Ian of hiding a dangerous side of himself. After having him steal Jenna's phone, Toby tells her that he never spied on anyone; the only thing he can make of Alison's assumptions is that she had something on him. Spencer stumbles across a trophy with Ian Thomas' name on it. Spencer sees dried blood at the base of the trophy and the girls inform the police. The next day at school, some police officers and a detective appear. They approach the Liars and ask for Spencer. In turns out that while failures to turn evidence into the police before were mistakes, in this instance, reporting to the police was the mistake.
The girls are questioned by the police as to why they think Ian is Alison's killer. Each of the girls lets Detective Breyer know about the video footage of Ian with Alison but not Spencer dating him. Spencer and Toby form an unlikely alliance, as the two grow increasingly suspicious of Jenna and her ties to a mysterious room at a local motel. Toby is staying at the motel to escape Jenna's wrath. Toby and Spencer stake the room out from the room next door for Jenna and end up falling asleep. They wake up and realize "A" set them up on wild goose chase.
Spencer is shaken when the investigation that’s focused on her leads to the police searching her home. They go through everything in her room, her jewelry, her closet, and even want to take her laptop, but her mother refuses on the grounds that it was not in the search warrant. Unfortunately, the police and her mother found out about Spencer's and Ian's past, making Spencer look especially guilty for having lied. Later, Ian volunteers to help Spencer run away before she's arrested. That night, her mother tells her that someone might be trying to frame Spencer.
As the town prepares for the annual Founder’s Day festival, Spencer’s family urges her to make a public appearance and help out at the church booth at the festival to improve her reputation. Her family also doesn't want Spencer to see Toby anymore. At the festival, she is trapped in a haunted house by "A". She is released by Ian and her family and is taken home. On the way, Spencer stops following when she catches sight of Toby. She runs straight into Toby’s arms and kisses him, disturbing her family.
After finding Ian's videos, Spencer decides to use it as a means to get him to confess to Alison's death. After Melissa is in a car crash, Spencer goes to the church to pick up her phone only to be confronted by Ian. She shows him the thumb drive and throws it to distract him. She is nearly killed by him in order to stage her suicide but someone pushes him of the bell tower. After the girls find her, the police arrive but Ian's body is no where to be found leaving the town to wonder what the girls are up to.