Getty/Nicholas Kamm Parkland activist David Hogg, 17, and his younger sister Lauren Hogg, 14, are writing a book about the Valentine's Day school shooting that turned high school students into national activists and launched the ensuing #NeverAgain movement. Their forthcoming book, "#NeverAgain: A New Generation Draws the Line" will be published by Random House this June. "This book is their statement of purpose, and the story of their lives," Random House said.