Viscontessa Lucia Sinistre is the grand-daughter of the Contessa Maria Sinistre. She inherited her grandmother's ability to control others with her voice. Because her name is really long, she prefers to be called Lucy.
Lucy Dexter was first introduced in this book. Nobody but Nero and Raven knew her relation to the Contessa when she came to H.I.V.E. The Gang took her under their wing over the course of the story, ultimately discovering Lucy's voice abilities when she saves Laura and Shelby from excecution.
In Zero Hour, Lucy is captured by the disciples and near the end, when overlord released the Nanites, and prepared to shoot Otto. When he pulled the trigger, Lucy cried out and dived into the bullet path, barging Otto out the way and ultimately taking 2 bullets high in the back. He told Laura to go and help raven, after telling the nanites to ignore someone with animus, Killing overlord. When Otto asked Lucy why she did it, she said: "Because there always has to be a choice.""and Because I fell for you the moment I met you." She then put her final strength into commanding Otto to leave her and save herself. He fought the urge for as long as possible, Kissing her on the forehead and gently lowering her body. he left and sealed the doors behind him. R.I.P Lucy Dexter - You Will Be Missed.