Mary Murphy feels like she's drowning. Her violent father is home from prison, and the social worker is suspicious of her new bruises. An aunt she's never met keeps calling. And if she can't get a good grade on her science project, she'll fail her favourite class. But Mary doesn't want to be a victim anymore. She has a plan: build a real submarine, like the model she's been making with Kip Dwyer, the secretly sweet class clown. Gaining courage from her heroine, Joan of Arc, Mary vows to pilot a sub across the Chesapeake Bay, risking her life in a modern crusade to save herself. 'Mary Underwater' is an empowering tale of persistence, heroism, and hope from a luminous new voice in middle-grade fiction.