Ollu is barger; a trader living and working on her mother's matriarchal boat, The Ark. When they lose all their trade goods in a storm and her Mum gets sick, the only way to save her mother's life and the life of her baby siblings is to make the most dangerous trade of her life. Ollu has to venture into forbidden waters, Bad Water, and she must go alone. With her old allies under attack, she finds herself reluctantly welcoming...