In Pretty Little Liars, friends Aria (Lucy Hale), Hanna (Ashley Benson), Emily (Shay Mitchell), and Spencer (Troian Bellisario) are drawn back together a year after the disappearance of their best friend, Alison (Sasha Pieterse). The four reconnect after Alison's murdered body is discovered, and they begin receiving threatening messages from an omniscient person called "A," who uses their deepest secrets as leverage to dictate their every move and imply their involvement in Alison's murder. The friends set out to unmask their anonymous tormentor and prove their innocence but instead get drawn into a series of mysteries that raises more questions than they answer about Alison's fate and the motives of the people they thought they knew best. The deeper they dig, the more ground "A" seems gain, staying a step ahead of them at ever turn and threatening exposure that could unravel their lives and the lives of their families, friends, and significant others.