Fifth grader Cassie has lived her whole life in Lower Manhattan. She knows every vendor, has explored every street, and as a New Yorker who's seen everything, knows that nothing can surprise her anymore. That is, until the morning of September 11, 2001. Cassie is in class when a plane hits the North Tower of the World Trade Center, where her mother works. She can see the smoke from her classroom windows, can feel the building shake. Without thinking, she dashes out of school to run to the tower. She knows every inch of that building - if anyone can save her mother, it's Cassie. But when the second plane hits the South Tower, and both buildings come crashing down, it will take more than street smarts to survive. NYPD rescue dog Ricky is a friend to all and hero to many. He's in a training session when the first plane crashes, and immediately springs into action. His task is to save as many people as he can find in the rubble. But as hope for survivors fades, he'll have to learn that sometimes heroism means helping people pick up the pieces of what is already destroyed. Together, Cassie and Ricky will have to work to save who they can, and survive the darkest day in New York City history