有剧透……剧透！请退避！个人猜测！
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虽然是根据小说改编的，问题是小说到现在也没有写完结局。但是，根据wiki百科，A是Alison，而死去的那个人是Alison的双胞胎妹妹。（高中时期的A是Mona，再然后发展出来另外一个A是Alison）然而呢，官网上说 电视剧没必要按照原著拍摄下去，而且原著没有写完……
所以，我猜测了一下……
1，在Arial回到小镇之后，4人才开始受到A的短信。
2，A 可以表示Arial
3， Alison 哥哥jason表示过房间里的Arial照片不是他拍的，而是Alison拍的。说明alison 和 arial 之间有什么秘密。
4，片头曲 也有暗示 arial 的意思，仔细看啊！
5，主题曲歌词也提到：两个人保守秘密，其中一个是死人。（暗示Alison 和Arial…）
6，无论4人有什么计划和活动，A都可以事先知道，那么A很可能就是4人其中之一。
7，另外3个人都受到A的打击伤害。金发女Hanna 被车子撞伤， 黑发女Spence被怀疑杀人犯，游泳女emily体内有兴奋剂……那么Arial呢，很幸运吧……
8，另外，几次A想要破坏Arial的事件都可以侥幸逃脱。比如，有一次A想让Arial母亲看歌剧，同时撞破她与老师约会，结果妈妈车子坏了…
暂时想到这几点……欢迎补充或否定……
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这里贴一下 wiki百科里面，作者打算写12本书。这是小说原著目前的结局：
Wanted
Hanna, Aria, Emily, and Spencer are shocked to learn of the existence of Alison's twin, Courtney, when she's introduced at a press conference. Courtney had spent her life in institutions due to "health issues" and her existence was kept secret by her family. Newly released, she attempts to resume her sister's life and begins tentative friendships with Ali's old friends, even striking up a romantic relationship with Emily, who is overjoyed. Courtney later reveals that she's actually Ali; that the real Courtney had pretended to be her on the night of Ali's disappearance, and she was the one who was killed.
Meanwhile, Spencer had begun to believe that her sister is Alison's killer, but Ali is revealed to be the real killer. The girl they were friends with years ago was actually Courtney, and the real Ali was stuck in an institution. Alison killed Courtney, attempted to kill the girls in the forest fire, killed Jenna, and now plans to kill them by setting the house on fire. The girls discover that Alison killed Ian and kidnapped Melissa, who they free before escaping the burning house. Trapped inside the house, Alison is assumed dead, although her body is never found.
The ending of the book suggests that Alison survived the fire and that she and her family have moved on to somewhere else.
Twisted
Spring break of junior year, the girls go on vacation in Jamica, where they encounter a girl who they believe is Alison, thinking she survived the fire. The girls are attacked by "Ali" on top of the hotel in Jamaica and in an attempt to save Hanna, Aria shoves Ali off roof, seemingly killing her.
A year later, the girls have parted ways once again. Aria has trouble dealing with the Kahn's new foreign exchange student, Klaudia, who creates rifts in Aria's relationship with Noel, wanting to steal him from Aria. In a fit of anger, Aria pushes Klaudia off a ski-lift, injuring her. Emily befriends a new girl, Chloe, and reveals that she'd gotten pregnant from her fling with Isaac and secretly gave birth to a baby in Philadelphia over the summer, which she gave up for adoption. Emily is now panicked about getting a swimming scholarship, her only option for college; Chloe's dad offers to help, but makes sexual advances towards Emily, which ruins her friendship with Chloe.
Patrick, a photographer, offers Hanna a modeling job, however he turns out to be a liar who blackmails Hanna with a racy photo of her. Hanna steals money from her dad's campaign fund to pay him off and frames Jeremiah, one of her father's campaign workers. Mrs. Hastings becomes engaged to Nicholas Pennythistle, and Spencer discovers that his son, Zach, is gay. She promises to keep his secret, but accidentally blurts it out after Mr. Pennythistle misunderstands a situation and accuses Zach of sleeping with Spencer. It revealed that Spencer also ruined the life of a girl she went to an academic summer program with in order to get into Princeton.
Throughout the book the girls are tormented with notes from a new "A," who knows what happened in Jamaica, as well as all their other new secrets. The body of the girl they pushed off the roof is found, and the girls realize that she wasn't Alison, and that they killed an innocent person.
Ruthless（这是第10本，2011年12月出版）
For years scandal has rocked Rosewood, Pennsylvania — and high school seniors Aria, Emily, Hanna, and Spencer have always been at the center of the drama. They’ve lost friends, been targeted by a ruthless stalker named A, and narrowly escaped death. And it’s not over yet.
Aria’s love life is on the fritz. Emily’s exploring her wild side. Hanna’s kissing the enemy. And someone from Spencer’s past — someone she never thought she’d see again — is back to haunt her. But none of that compares to what happened last spring break. It’s their darkest secret yet and guess who found out? Now "A" is determined to make them pay for their crime, and the only thing scarier than "A" is the fear that maybe, just maybe, they deserve what’s coming to them.
之后，还有2本书，才会看到大结局。
