At night, the Liars are shown at a establishment discussing the fact that the truth about who was behind Uber A's mask never came out. Lucas appears in a white tuxedo tap dancing, while Jenna is riding a horse. The girls begin to talk about random and funny things until snow starts to fall from the sky and it is revealed that the previous scenes were the product of Mona's imagination, who is holding a snow globe in an unknown room at the Welby State Hospital. An "A.D." then appears and Mona drops the globe, breaking it instantly, as she gets surprised when she realizes who's there.
One year after the events of the previous episode, Ezra and Aria are discussing their book and its soon to be film adaptation in the Warner Bros. Television backlot. Now famous due to their book's worldwide success, they kiss and are photographed by a bunch of fans in a cart (staff writers of PLL in a group cameo). The scene then jumps to the DiLaurentis house, where Emily and her high school sweetheart Alison are living a family life, taking care of the recently born Lily and Grace. Alison tells Emily she is going to a meeting, but instead she goes to the Radley to talk with Emily's mother, Pam, about their relationship and how both Alison and Pam are happy about it. Spencer and Melissa have a sisterly moment together as Spencer sees Toby approaching her pickup truck which used to be Toby's pickup. They talk about his return to Rosewood after he left to travel around countries with Alison's half-brother Jason. At the school, Alison discusses with Addison, who jokes about Alison's friend Aria. While leaving the room, Addison is pressed down by Alison, who threatens her. After, Alison observes Addison's clique while Emily approaches and the two ask student Claire if Addison was bullying her, which she denies. Jenna then approaches Addison, who jokes about her blindness, and Jenna argues with her, saying she can smell a bitch a mile away. Addison's clique leaves and Jenna passes by Alison and Emily, who smile to her in joy. After Mona was released from the psychiatric hospital, she is accepted by Hanna in her loft, which jeopardizes Hanna's relationship with Caleb, who thinks Hanna has done enough for Mona. Hanna and Caleb leave Mona in the apartment to go to a surprise dinner planned by Spencer, who remodeled the Lost Woods Resort into a modern establishment. There, they eat and have fun remembering good times in their lives. The camera soon shows someone in a black hoodie watching them. The person turns around and is revealed to be Melissa. However, she walks in the forest and takes off Melissa's mask, revealing herself to be Mona, and starts talking with A.D. through FaceTime. The couples, meanwhile, retire to their rooms. Later, Spencer finds Aria crying in the living room, who reveals to the Liars that she sterile. The next morning, Hanna and Caleb arrive home and find Mona gone only to have her appear from the bathroom, claiming to have been in the shower. Meanwhile, Aria reveals her condition to Ezra.
In the jail, Spencer visits Mary and asks her for help. Later, in Aria's rehearsal dinner, Hanna takes Mona with her, and the Liars — and Hanna's mother — condemn it. Hanna manages to convince her friends to give Mona a chance. Ezra and Byron talk about Ezra's marriage with Aria, and Byron gives him his blessing. Later, Alison proposes to Emily who accepts.
Spencer shows up at Toby's room at the Radley and they have sex. Right after, she is at the Barn and is knocked down by Mona. She then wakes up in the floor of a modern strange room which resembles the one from "Game Over, Charles". She looks at herself in a supposed mirror, but the person she's looking at doesn't follow her movements, frightening her. Mary Drake then appears and injects a sedative into Spencer, while she looks on in shock at the woman who looks exactly like her. Spencer soon awakens and comes face to face with her long lost identical twin sister named Alex Drake who is also revealed to be their tormentor known as "A.D" and the third daughter of Mary Drake who was given up for adoption by her mother to get out of Radley. She lived in London on the streets where she came across Wren Kingston whom she dated and learned about her twin sister and her family. She soon met her half sister Charlotte and the two instantly connected as well as befriending Archer Dunhill who had met Charlotte on the plane after she left Rosewood to get away from being arrested for killing Wilden. Once Charlotte left, Alex soon came to Rosewood and learned about her half sister's fateful death which triggered her to become "A.D" and also she was jealous of the life that Spencer lived. She also posed as Spencer multiple times when she kissed Toby in "The Darkest Knight" and had sex with him in "Choose or Lose" and appeared to Hanna when she was being held by Alex in her dream sequence for confessing to killing Charlotte. Alex also shot Spencer in the blind school and got Wren to shoot her in the shoulder so she would be like her twin sister and soon enabled a team consisting of Mary, Jenna, Sydney, Aria and Wren and reveals their motives. She had used Sydney who stole from her bank and blackmailed her, Alex promised Jenna to pay for her eyesight if she joined, Aria because of the file that she reported about Ezra, Mary because she had no other choice and Wren who had given her information about the Liars. She also reveals that she killed Wren who discovered her revenge plan and tried to back out but also didn't call her Spencer who she wanted to be and turned his ashes into a diamond necklace.
Alex goes to the Liars posing as her sister where Ezra is missing. Aria begins to worry that she will be ditched at the altar because of her infertility. Alex holds Emily and Alison's babies and secretly reveals to no one listening that Wren Kingston is their biological father and she impregnated Alison when she was at Welby. Ezra is also locked up with Spencer after he discovered about Alex's existence. The Liars soon find out about Alex Drake and that Wren visited Mona and was intent on killing her but she promised him that she could get Mary out of prison. They learn the location of the lair which is underneath Toby's house that he built. Ezra and Spencer escape but find that they are still being held underground just as Alex, wielding an axe, appears and knocks out Ezra and attempts to kill Spencer. The Liars, as well as Toby, arrive in time to come face to face with the identical twins. Toby struggles to decide which one of them to arrest until he asks Alex what her favourite poem is but Spencer instead gives the answer thus confirming the identity of the two and Alex is arrested by police along with Mary. Aria finally marries Ezra soon afterwards.
The Liars are seen in the town square exchanging goodbyes as Aria prepares to leave for her honeymoon when Hanna reveals that she is pregnant. In France, Mona is seen running a doll shop and her boyfriend is the police officer who arrested Alex and Mary who Mona has now held captive in her personal dollhouse thus revealing that Mona has won the game that she created. Meanwhile, a new group of Liars are at a sleepover and one of them notices their leader, Addison Derringer, missing and a girl dressed as Spencer emerges and reveals that Addison is missing and the series ends when she says "I think that I heard a scream".
Tropes
- Babies Ever After: Hanna is pregnant.
- Back for the Finale: Ella, Charlotte (in flashback), amongst other Characters.
- Bed Trick: Alex pretending to be Spencer having sex with Toby. And did so a few episodes ago.
- Bookends: The Final scene recreated the first scene in the Pilot.
- Creator Cameo: I. Marlene King makes an appearance as the photographer at Aria and Ezra's wedding.
- Chekhov's Gunman: The policeman who arrested Alex moves to France with Mona.
- Deadpan Snarker: Ezra tells Spencer that he goes into Sarcasm Mode when he's in Danger.
- Dropped a Bridge on Him: Wren
- Earn Your Happy Ending: At least they won't be getting any texts from 'A'.
- Evil Brit: Alex!!!
- Evil Twin: Alex Drake to Spencer.
- Expy: Addison to Alison.
- Fake Brit: Troian Bellisario playing a British Alex.
- Loving Details: How did Toby know which twin was Spencer and which was Alex? Ask about their favorite poem.
- Meaningful Name: Alex Drake, or AD.
- The Reveal: It is finally revealed that Alex Drake is AD.
- Series Finale
- Sequel Hook: The final scene recreates the pilot where Alison disappears, but instead It's Addison in Alison's place.
- Time Skip: Takes place a year after 7x19.
