<P> One week later, Spencer has recovered and A.D. sends Jenna to confess to the cops that Noel wanted money Charlotte left Jenna for another eye surgery, killed Sara and tried to kill Jenna in the blind school . Peter returns and reveals that Mary is the one who killed Jessica . Hanna and Spencer follow the trail of a private investigator he hired to find Mary and bump into Ted who reveals he has been hiding her as she is his college fling with whom he conceived Charles . Mary reveals to Spencer that Peter and Jessica were planning to kill her, thus she used his pills to kill Jessica . A.D. then uses Emily's stolen eggs to impregnate Alison, as a way to further torture the liars . Meanwhile, A.D. hires Sydney Driscoll as their helper and she fakes being A.D. to recruit Aria into joining the A.D. team . Aria is forced into playing and becomes A.D.'s new helper, destroying Emison's baby nursery and leaving an "A" message in Spencer's house, until the Liars catch her in the act and she defects . Mona, who is becoming addicted to the A-game again, reveals that she tried to scare Charlotte into not resuming the A-game but Charlotte attacked her and she killed her in self - defense . Mary confesses to Rollins and Jessica's murder . A.D. ends the game as they have finally learned that Mona was Charlotte's killer . </P> <P> One year later, Mary escapes from prison and Mona is released from Welby but rejoins the A-Team and is sent to kidnap Spencer, who comes face - to - face with A.D.--Alex Drake, her twin sister . Mary reveals she sold Alex to a London family to get out of Radley . Alex ran away and met Wren who revealed everything about Spencer to her and introduced her to Charlotte who left her everything . She became A.D. to use the Liars to find Charlotte's killer and killed Wren as he always saw her as Alex while she wanted to become Spencer to have her "perfect life". She explains that Sara was looking for Charlotte's false treasure in the Radley which was actually the secret fall and Jenna recruited Noel to look for "Charlotte's sister". Jenna uses her enhanced sense of smell to figure out "Spencer's not Spencer" and alerts Toby who tells the others . Mona reveals to them that Wren was going to kill her but she convinced him she could get Mary out . The Liars, Toby, Mona, and Caleb come face to face with Alex and Spencer as they cannot tell them apart, until Toby makes the distinction by asking what Spencer's favorite poem from a book she gave him . Mona tracked A.D.'s location has a cop arrest her . The Liars then say goodbye to one another as Aria leaves for her honeymoon with Ezra . Mona moves to Paris and the "cop" is revealed to be her boyfriend who has imprisoned Alex and Mary in her basement dollhouse . In the finale moment, a new set of liars are awaken to find their leader, Addison, has just gone missing . </P> <Ul> <Li> Troian Bellisario as Spencer Hastings and Alex Drake </Li> <Li> Ashley Benson as Hanna Marin </Li> <Li> Tyler Blackburn as Caleb Rivers </Li> <Li> Lucy Hale as Aria Montgomery </Li> <Li> Ian Harding as Ezra Fitz </Li> <Li> Laura Leighton as Ashley Marin </Li> <Li> Shay Mitchell as Emily Fields </Li> <Li> Andrea Parker as Mary Drake and Jessica DiLaurentis </Li> <Li> Janel Parrish as Mona Vanderwaal </Li> <Li> Sasha Pieterse as Alison DiLaurentis </Li> </Ul> <Li> Troian Bellisario as Spencer Hastings and Alex Drake </Li>

What happened in last season of pretty little liars