When the massive metal tank filled with sticky brown molasses that rises up over her crowded North End neighborhood explodes, young Carmen must fight for her life, as a tsunami of molasses rushes through the streets.

In 1899, a fifteen-year-old orphan named Hannah obtains employment as a servant in the home of one of Boston's wealthiest families, where she meets a noted portrait painter who seems to know things about her that even she is not aware of, and when she accompanies the family to their summer home in Maine, she feels an undeniable pull to the sea.

Spirited fifteen-year-old horse lover Rachel Selby determines to become a veterinarian, despite the opposition of her rigid father, her proper mother, and the norms of Boston in 1872, while that city faces a serial arsonist and an epidemic spreading through its firehorse population.