Never Have I Ever by Sara Shepard

Never Have I Ever, published August 2, 2011, is the second book in the four book thriller series The Lying Game by Sara Shepard, about twin sisters separated at birth.
In this second installment of Sara Shepard's "The Lying Game" series, Emma Paxton finds herself delving deeper into the mysterious life of her- now dead- twin sister, Sutton Mercer. The unknown murderer seems to be watching her every step and she must carefully maneuver maintaining a low-key investigation into her sister's death whilst not alerting the killer to her intentions.
Emma continues to pose as her twin sister, Sutton. She continues to find out clues or anything to find out who has killed Sutton. Between finding clues and who the actual killer is, she continues to play, The Lying Game. The series follows Emma, a foster kid who can't catch a break who finds out she has an identical twin sister, Sutton, who unlike Emma was adopted by wealthy parents and is seemingly living an ideal life. After their initial meeting, Sutton talks Emma into stepping into her life for a few days while she pursues a lead on their birth mother. Initially excited to do this favor for her sister, Emma soon learns that Sutton has gone missing and could be in trouble. Now, Emma must decide whether to come clean to Sutton's family and risk her own safety in the hope of uncovering her twin sister's true whereabouts, along with the truth about why they were separated in the first place... (Summary by Wikipedia)

The Lying Game by Sara Shepard

The Lying Game is a drama television series set to air on ABC Family. The show The Lying Game is based on a series of novels of the same name by Sara Shepard. The network green-lighted the series in February 2011, with an August 15 premiere planned.
New York Times bestselling author Sara Shepard's new series The Lying Game, published December 7th 2010, weaves a mystery of long-lost twins, mistaken identities, a duplicitous circle of friends, and cold-blooded murder. Combining juicy plot lines, to-die-for lifestyles, a tangled web of friendship and romance, magnetic characters, and sharp-witted narration from the afterlife, The Lying Game is an alluring cross between Pretty Little Liars and The Lovely Bones.
Foster kid Emma Paxton has only just discovered Sutton Mercer, the wealthy twin sister she never knew she had, when Sutton drops off the face of the earth, asking Emma to cover for her at home, school, and with her friends—just for a few days. The story is about foster child Emma Paxton, who comes to believe she has a twin sister. She goes on Facebook, and sends a message to the girl, Sutton. Sutton writes back saying that they need to meet. However, Sutton is actually dead. Emma goes to the Sobino Canyon, Arizona. While waiting for her sister, she is attacked by a group of people. They take her across the street, and remove the burlap sack over her head. That's when Emma finds out that it's just Sutton's friends playing a prank.
The friends believe that Emma is Sutton, and take her to Nisha's party. Back at Sutton's home, Emma still goes on with the charade as being Sutton, since they are identical twins... (Summary by Wikipedia)

Pretty Little Liars by Sara Shepard

Pretty Little Liars is a series of young-adult novels by American author Sara Shepard, beginning with 2006's inaugural entry of the same name. The series Pretty Little Liars follows the lives of four girls – Spencer Hastings, Hanna Marin, Aria Montgomery, and Emily Fields – whose clique falls apart after the disappearance of their leader, Alison DiLaurentis. Three years later, when the girls are juniors in high school, Alison's body is found, and they begin receiving various messages from someone using the alias "A" who threatens to expose their secrets and get revenge.
The Pretty Little Liars novels explore several serious issues such as bullying, murder, eating disorders, homosexuality, peer-pressure, infidelity, and mental illness. Moral ambiguity and the consequences of lying are featured prominently in the series: The girls constantly create their own problems through their unwillingness to tell the truth about certain events and misdeeds they have done. The novels have frequently appeared on the The New York Times Best Seller list. In 2010, a television series based off the novels began airing. Stunning, the eleventh book in the Pretty Little Liars series, was released on June 5, 2012. A twelfth book, Burned, is scheduled to be released on December 4, 2012.
The series Pretty Little Liars is loosely divided into three arcs of four books each, chronicling the introduction and reveal of each "A". The series follows the lives of four teenage girls — Aria Montgomery, Emily Fields, Hanna Marin, and Spencer Hastings — whose clique falls apart after the disappearance of their leader, Alison DiLaurentis... (Summary by Wikipedia)

Perfect Pretty Little Liars by Sara Shepard

Perfect is the third book of Pretty Little Liars, a series of young adult novels by Sara Shepard.
Now homeless, Aria goes live with her new boyfriend, Sean Ackard. Still seeing Ezra, their relationship is broken up when Sean informs the police, having found out the secret from "A". Emily plans to go to the police to stop "A", which leads to "A" taking revenge by outing her to the whole school. Emily's parents threaten to send her away if she does attend a "de-gaying" program, however, Emily realizes she can't change who she is. Spencer is nominated for a Golden Orchid Award for the essay she plagiarized, which "A" threatens to expose. Spencer comes to believe she might have killed Alison after discovering she suffers from rage-induced blackouts. Emily is in a secret lesbian relationship with her new neighbor, Maya, as Spencer has flashbacks to the night of Ali's death. Aria tries to keep her father Bryon's affair a secret from her mother and brother while Hanna deals with her social downturn by resuming her bulimia. Spencer remembers pushing Ali into a stone wall after a heated argument, and fears that she is the one who killed her. After Aria ignores "A's" threats, "A" reveals her father's affair to her mother, who kicks Aria out of the house.
Hanna and Mona grow apart and Hanna becomes involved with an unpopular boy named Lucas. After getting humiliated at Mona's birthday party, Hanna receives a text from A and recognizes the number. She intends to reveal the true identity of "A" to the other girls, but is run down by "A" before she can do so... (Summary by Wikipedia)

Flawless Pretty Little Liars by Sara Shepard

Flawless is the second book of Pretty Little Liars, a series of young adult novels by Sara Shepard.
In the aftermath of Pretty Little Liars, Spencer, Hanna, Aria, and Emily are more desperate than ever to discover the identity of "A", who is still taunting them with the threat of exposing their many secrets. Their personal problems continue; Aria begins a relationship with Sean, Hanna's ex, and faces the problem of her dad pulling away from the family while continuing his affair with his student, Meredith. At the same time, her little brother, Mike, also finds out. Emily ends things with Maya, and begins loving a boy named Toby Cavanaugh. Hanna begins to have many problems with her best friend, Mona, and deals with stress brought on by her failing body image, the loss of Sean, and the re-appearance of her father in her life. And Spencer continues her secret relationship with her sister's ex boyfriend, Wren. The girls are confused and on edge after Alison's funeral, anxious to stop "A" and keep their secrets buried. "A" taunts Emily about her sexuality and growing feelings for Maya. Hanna is pressured by "A" to tell Naomi and Riley about her eating disorders and is shocked to discover her ex-boyfriend Sean is now pursuing a relationship with Aria. Aria, who is still seeing Ezra, is threatened by "A" to either get rid of Meredith or reveal her father's affair. Spencer plagiarizes one of Melissa's essay for a class, and "A" subsequently reveals to Melissa that Spencer has been secretly dating Wren, Melissa's ex-boyfriend... (Summary by Wikipedia)

Wanted Pretty Little Liars by Sara Shepard

Wanted is the eighth book of Pretty Little Liars, a series of young adult novels by Sara Shepard.
In Rosewood, majestic estates sprawl for acres, and Tiffany toggle bracelets dangle from every girl's wrist. But not all that glitters is gold, and the town harbors secrets darker than anyone could imagine—like the truth about what really happened the night Alison DiLaurentis went missing...
Back in middle school, Ali plucked Emily, Hanna, Aria, and Spencer from obscurity and turned them into the beautiful, popular girls everyone wanted to be. Ali was the best friend they ever had. But she also made them do terrible things and taunted them with their worst secrets. Now, three years later, all their questions about Ali have finally been answered and they can put this awful chapter of their lives behind them. Or so they think.
In the dramatic conclusion of Sara Shepard's bestselling Pretty Little Liars series, Emily, Hanna, Aria, and Spencer could get everything they've ever wanted—unless A has one more horrifying twist in store.
With Alison's killer on trial, the girls think they can relax. They're shocked to learn of the existence of Alison's twin, Courtney, when she's introduced at a press conference. 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. Courtney later reveals proof that she is the real Alison, explaining that her twin, Courtney, pretended to be her on the night of the murder. Although skeptical at first, the girls slowly begin to trust Alison... (Summary by Wikipedia)