After their friend Alison, missing for more than three years, turns up dead, four former best friends, each of whom had a secret known only by Alison, begin receiving frightening messages from someone identified by the letter "A."

Ava, Caitlin, Mackenzie, Julie, and Parker are all driven to be perfect--no matter the cost. At first the girls think they have nothing in common, until they discover that they all hate the same person: handsome womanizer Nolan Hotchkiss, who's done things to hurt each of them. They come up with the perfect plan to murder Nolan--jokingly, of course. They'd never actually go through with it. But when Nolan turns up dead in the exact way they'd discussed,...

When a rich bully and someone else dies, Mackenzie, Ava, Caitlin, Julie, and Parker wonder if they're being framed. Or are they about to become the killer's next targets?

When one of their tightly-knit group mysteriously disappears, four high school girls find their friendship difficult to maintain when they begin receiving taunting messages from someone who seems to know everything about their past and present secrets.

When Aerin is kidnapped by a killer she knows all too well, her friends Seneca, Maddox, and Madison have four days to solve a series of related cases in order to secure her release.

"It's springtime in Rosewood, but while everyone else is searching for the perfect prom dress, Hanna, Spencer, Emily, and Aria are on a different kind of hunt: They're looking for A...Hanna puts her campaign for prom queen on the back burner to volunteer at a burn clinic, where one of A's victims is recovering. Emily digs into Ali's past at the mental hospital with some very crazy consequences. Spencer contacts an amateur private eye to help her stalk...

Seventeen-year-old Emma Paxton steps into the life of her long-lost twin Sutton to solve her murder, while Sutton looks on from her afterlife.

Struggling to return to normalcy after surviving Alison's attempt to kill them, Spencer, Aria, Emily and Hanna endure a series of disasters before realizing that they are being stalked by a new "A" who knows all of their secrets.

After surviving their latest encounter with A, high school seniors Aria, Emily, Spencer, and Hanna must try to convince the police that the real A is still on the loose, all while trying to stay alive.

Watching from beyond the grave while her long-lost identical twin, Emma, assumes her identity, Sutton Mercer witnesses the discovery of a dark family secret and realizes that someone from Emma's past may be her own killer.