Four little liars are at it again. Aria's love life is on the Fitz???ahem, 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 these pretty little liars did on their last spring break. It's their darkest secret yet. And guess who else knows?